I have the 2000, which has the longer part in the front and then the small seat in the back. I thought there was a GTX seat with the hump that fit the GTI but can't really remember where I read that.
I like your custom seat you had made. There aren't any shops local to me that would be able to make that.
My plan was to keep it looking exactly like stock. I need a seat cover and it looks like I'll have to go with a custom cover. If I'm going to do that I'd like to either find a touring seat, if they exist, and have it covered. Or, build onto my seat they way you did, and have it covered. A custom seat would probably be more comfortable than whatever touring seat was available back then.