Quick comment -
The gel sheets may or may not stick to the vulva area - it should on the labia majora, maybe the labia minora- but not sure about the mucous type skin of the vagina. We might have a lot to learn from burn patients and their recovery process.
I was even wondering whether liquid bandage might form a layer that would protect from the urine?
As a long time camper - who tent camped for umpteen years - we had started using pee jars to make night time bathroom trips easier. A pee jar might be an empty plastic mayonnaise jar or peanut butter jar, held against the vaginal labia to catch the urine, then capped and thrown out. The urine, though, still gets the vulva area wet.
I wonder if you could devise a much smaller urine diverter, devised to fit your body’s structure and urethra. If you’ve ever gotten a close look at the urethra opening it’s really small - and maybe it’s possible to hold a tube against it to direct the urine away? Maybe? I’m thinking a 1” plastic tubing with something like Sugru around the edge to soften it (Sugru is silicone putty, hardens to soft touch, non-toxic, adheres to most surfaces - need to check the type tubing you’re using - and washable, get it at major hardware stores). The problem is you have to get your hand down there every time you pee, and the tube would need to be washed after each use. But if skin integrity is a long term issue, it might be worth it? Maybe?
Sorry, gotta go for now.