I have just got a solo seat for my 2005 Sportster 1200c second hand. It is not quite the right one but close. My issue is that it sits on a plastic electrical box that is in between the vee of the frame between the mudgard and the tank. 

Will this affect the box, I wonder if the box gets hot??. The dual seat plastic base is shaped over the said box.

Mate mine has the same box (ignition module). I wouldn't use it. Be nothing worse than pushing the harley home. Can't find the correct one mate?