I hear you. I've also got back issues. I took the stock GV seat to a professional car/motorcycle re-upholsterer and he said it was one of the worst motorcycle seats he had ever seen. I thought he might be able to reconstruct the seat pan and re-upholster it, but he said he didn't want to touch it because there wasn't much to work with.
I'm hoping my local Kymco dealer can order that Luxury GV Seat for me. I ride my red GV a lot, and it would be nice not having to stop every 30 minutes to stretch out my back.