Thanks for this question, in the last years I have worked or am working with people approaching admission to profession according to C 603. In each case, I said I hoped the Rule they are or were writing would truly become an embodiment of the way God has been working in their lives and speaks to them in this canon. After all, the Canon describes a way of life where God is central, where everything is focused on letting God be God, and particularly, focused on letting God be God-With-Us in the silence of solitude through assiduous prayer and penance, etc.
As I have written before, the Rule should reflect not only the letter (the literal terms) of the Canon but the singular lived experience that stands at the heart of the life it governs. This experience of letting God be God is the essence of what it means to be created, called to be, and made truly human as imago Christi. The solitary hermit in the consecrated state perceives and commits to the truth that this best occurs for her according to the terms and conditions that define her vocation canonically and without the community context that requires Rules (or Constitutions) to be shaped more generically.When I write (indirectly) about these personal things in my Rule, it is because I have a vision of the solitary life that appreciates both the silence of solitude and eremitical life together as a gift of God for myself, and for far more than myself! In a world fraught with isolation, woundedness and trauma, division, and noise on every level and of every possible type, a hermit living and exploring "the silence of solitude" as part of what it means to be truly or authentically human becomes a gift to that same world. More immediately, the hermit's Rule becomes the story of God working in her life and provides the outline of a vision of how to continue participating in that story! It is a vision she commits to grow into with God wherever this takes her.
Canon 603 has a number of other requirements and each of them needs to be addressed in a similar way. These need to 1) imply one's own story with God, and 2) provide a vision of the life that may serve others who are searching and waiting to hear the Gospel as the answer to their own journeys --- even if they never step anywhere near a hermitage. What is absolutely critical is that in some way the hermit writing the Rule combines the requirements (central elements) of Canon 603 with her own life story, not because she cannot let go of her life before the hermitage, but because in every way, the Rule she is proposing to live indicates the continuation and fulfillment of a long journey towards redemption by God's love. It spells out a coherent way of living out the victory of that redemption as it has unfolded to bring her here and still continues to unfold in this new context and commitment. This is what it means to have a vocation; this is the vision she must hold onto when living that vocation becomes especially difficult or demanding. It is who she needs to be as she determines what she will also do to witness and continue responding to that Divine call.As something of an aside, when I submitted my first Rule to my diocese back in @1984, it was sent off to a canonist to read and approve. She had a couple of comments regarding theology and then an observation about the nature of the document as a whole. She noted that it had a rather personal feel to it "but that in Rules of this sort" that was perfectly acceptable. Still, I remember feeling like her approval on this point was not unalloyed. When I look back at that Rule today, I find it kind of laughable; it was certainly inadequate. The irony is that that personal tone and nature, something that was pretty new at that time (since such documents and the Canon that called for them were pretty new at this time) later was perceived as a key to discerning such vocations and providing a way of working out the formation of c 603 hermits.