Got it! Thanks Jim!!!!

Now I need to go break out my tape measure,,,

Dug up the Utopia directions,,, 16 3/4 from rear of seat,,,

http://www.utpr.com/f6binstallation.html

Surely,,, between the 2,,, one of 'em (or both!) will avoid any conflict with my seam!!!

(Dadgummit,,, my wallet is feeling lighter by the minute!! )