This all sounds completely reasonable to me, and I love the suggestions you've made! Particularly that in-game deaths and all subsequent bodily alterations will further limit his magical potency (I also think it would be very appropriate for him).

I'll make a note of these points in my application and put together a list of his other forms as well as dust off my opt-out/permissions post to help avoid Endwalker spoilers for anyone who may still be going through the MSQ or who would like to avoid specific content in general.