Heres another option. They do make a sundowner solo seat. I've never had the solo version, but the 2 up version is great.

 

I've got a mustang square back for riding two up and its super comfy.. maybe ill just get the tripper and be safe. The stock seat makes me feel like I'm sitting on my tail bone as well. Thanks for all the replies so far guys.. I like hearing all the diferint imput.