Mike
Very helpfull information and photos. I'm like you with the rear-end. I have put a Ultra seat with adjustable back rest on my SERK and it helped but an hour or so and I have to stop and rest butt. At first I didn't realize you have to ship your seat until I found the section explaining how it worked. I think if I understand correctly mine would run around $600 for I don't ride anyone and could use my stock backrest. If it works it's a no brainier even for that amount of money. Guess I will start looking for some mad money.
Oh yea, I'm the opsite end from you, I'm 5'7" and 175 lbs. I can see how the wings would help the butt cheeks. Looks like it makes it feel more like a chair seat.
Again Thanks for you help!!
Bob