Sure, happy to do so. Let me point out that the way I would answer the question of validation depends on the meaning or sense of the term "validation" used (there are several) and also the form of eremitical life one was addressing. (Throughout this answer I will NOT be addressing so-called semi-eremitical vocations but solitary eremitical vocations.) So, for instance, if a non-canonical hermit was approaching a bishop seeking to have her vocation "validated" by the church by being admitted to canonical profession and consecration, I would be the first to point out that c 603 is not necessary to do that in this case, and that, in fact, it could not be used either to validate or to truly invalidate such a vocation.** It is likely her bishop would do the very same thing. The call to non-canonical (or privately dedicated) eremitical life is the oldest form of eremitical life in the church and it continues to be a VALID form of eremitical life in the present as well entirely apart from c 603. (That is, c 603 does not and is not meant to replace it!!) I have said this in one way and another in my writing on eremitism for the past 17 years!!
The term validate has several different meanings, including: 1) to check or prove the validity or accuracy of (x or y), 2) to demonstrate or support the truth or value of (v or w), 3) to make or declare legally valid, and 4) to recognize or affirm the validity or worth of a person, their feelings, or their opinions, and to cause a person to feel valued or worthwhile. I think all of these forms of validation can apply to non-canonical vocations to eremitical life without benefit or need of c 603. In other words, c 603 does not do these things for any non-canonical eremitical life. Rather, c 603 is irrelevant to the validity, value, and legal standing of the non-canonical eremitical vocation. These are established in other ways, namely, by virtue of the rights and obligations conferred in baptism itself. In baptism one is (or may be) made free and empowered by the Holy Spirit to live non-canonical eremitical life. That life is validated in living it well as a representative of the people (laity, λαοσ) of God in the baptismal state alone. ("By their fruits, you shall know them"!!)
But what if the Bishop or priest were speaking of an ecclesial vocation, a public and canonical vocation to live eremitical life in the name of the church? Would the answer to the question as to whether c 603 validated these vocations be the same? Here we need to say no. If a bishop/priest were speaking of these specific vocations, and claimed c 603 did not validate them, that bishop or priest would be wrong. Of course it is true that "By their fruits. . ." applies here too, but, c 603 was created and made normative precisely to validate the ecclesial vocation to solitary eremitical life at least in senses 2, 3, and 4 -- although #4 applies not to the hermit herself, but to the vocation to which she is called. Canon 603 does not apply to the validity or worth of the individual person living the life or to her opinions, etc. The value of the person is presupposed, no matter the form of eremitical life being lived. (As I have also said a number of times, I live eremitical life in the name of the church; I do not write in the name of the church, nor do I suggest that my opinions or writing about this life necessarily have the same kind of validity as the vocation does. Writing as part of the eremitical life can be a valid expression of one's canonical vocation, of course. What one writes must be validated separately.)I think I can also argue that c 603 also generally establishes validity of any eremitical life in the church today in the first sense of the term validate above since all hermits tend to look at the central elements of the canon to discern whether or not they are living a valid form of the life (assiduously prayerful and penitential, marked by stricter separation from that which is estranged from or antithetical to Christ, marked by the silence of solitude, and lived for the salvation of others). Still, some characteristics of the canon are not lived by all hermits (supervision of bishop, Rule written by the hermit, profession of the evangelical counsels, and consecration by God mediated by the Church, for instance) so the canon only serves in a very general and informal way to validate non-canonical eremitical lives in the church.
The bottom line in all of this is pretty much what I have been saying since I began this blog almost 17 years ago. No one needs Canon 603 to validate a call to non-canonical eremitical life. Their baptism gives any person the right and freedom to follow such a call at any time in any place. No bishop can require that non-canonical hermits in his diocese seek canonical standing under c 603!!! He has no right to do so, and no really good reason either. Were he to try this he would be suppressing a valid God-given eremitical vocation in the lay state. Non-canonical eremitical life is a valid, Spirit-breathed vocation in the church, and has been since the third Century and more. However, if a person wishes and feels called to live an eremitical vocation in the name of the Church and be considered a solitary Catholic Hermit (not a solitary Catholic AND a hermit, but a Catholic Hermit!!), then yes, c 603 is used to profess, consecrate, and thus also to validate the solitary eremitical vocation lived publicly with public rights, obligations and expectations.I sincerely hope this is clear and helpful!!
** There is one exception to this, however. Is IS possible to use c 603 to invalidate non-canonical eremitical vocations but ONLY if it is misused!! If c 603 is used as a requirement for every eremitical vocation instead of just for solitary consecrated (i.e., canonical) eremitical vocations, then it will invalidate every non-canonical vocation. Fortunately, c 603 was never meant to do this, but instead to offer the church a means to honor a gift she had lost sight and esteem for over the centuries. Every person who feels called to solitary eremitical life is free to pursue it in a non-canonical form.
Living this vocation in the name of the Church requires a public commitment, however, and God's consecration along with other conditions constituting a stable state of life. This does not indicate a lack of humility on the canonical hermit's part, nor on the Church's. Instead, it recognizes the truly great challenge and gift such a life is to every person touched by such a call. To commit to becoming truly human in a solitary relationship between a human being and her God in the silence of solitude is almost unimaginable to most people today. To do this as an expression of the Gospel of Jesus Christ even more so. With canonical standing, the Church assures the conditions that nurture success in this.