Luke-
It sounds like you have put quite a bit of thought into this, so I don't have much to add.

If possible, put 'swimming pool' into your list of practice spots.
A nice (warm) pool is definitely the place to work on your roll and get wet.
Usually (for me) the problem in the pool is 'too warm' which is just fine if I'm doing a lot of 'gettin' wet'.

A neoprene tuilik (I have a Brooks) adds quite a bit of buoyancy (over your PFD), which can certainly help with starting balance bracing and sculling.
That might be something to keep in mind if you are choosing between Gore-Tex and neo.
I've built projects with both (Goretex jacket, neo sprayskirts), and neo is a bit easier in some ways, because it stretches, though the gluing is smelly and can be a bit messy if you are not careful.

I think the best strategy for practicing and paddling your SOF would be to have a capable partner and to practice your Eskimo rescue and other techniques, AND stay in warm water and close to shore. A bit of anxiety and a new boat, paddling solo, can be a stressful situation, and if you 'tighten up' it is even harder to stay in balance and have control (and fun).
It can be surprisingly difficult to swim ashore, depending on the spot you are in and what you are wearing, and towing a boat, so be careful!
I don't know what type of SOF you are building, or if you are an experienced paddler in other kayaks; if not, some lessons/practice in other boats might be a good idea.

One more thing- please ignore the 'fashion' and put deck lines and end toggles on your SOF - you may welcome them some day.