I think everyone is overlooking part of the OP’s question, and that is their question of what is licit.
The issue of licit would, I would think, rest on whether or not the OP has a canonical requirement to say the Office.
If there is none (and I presume there is none) then the matter of licitness would seem to be irrelevant. Thus, the Op could, if they desired, use something such as the publication The Magnificat, which has a truncated version of the LOTH. It would be less than the full LOTH, but not illicit to say.
However, it would not be recitation of the liturgy of the LOTH, as it was less than what is set out. It is about like going to Mass; if one only stays for the OT and NT readings and then leaves, one has not attended Mass; on weekdays there is no requirement, so it is not “illicit”; but neither is it attending Mass.
The same would seem to apply to the LOTH with the individual adding readings, or more psalms, or more canticles; if one has no canonical obligation, “illicit” does not apply; but neither does it seem to be participation in the LOTH, but rather a prayer format specific to the individual including psalms, a canticle, a reading, petitions, etc, plus whatever else one wants to add.
So if the OP desires to recited the LOTH - the 4 week cycle, (or for that matter, the two week cycle) according to the rules laid out for the specific community one follows - Benedictine or otherwise), then the OP should stick to the LOTH as laid out. Then take a break, and return to prayer with whatever other prayers, readings, psalms, canticles and etc one desires; but separate it off of the LOTh. One can also add some spiritual reading, or other spiritual exercises.
But if one has no canonical obligation, then the term “licit” seems misplaced.