I am considering a hitch for this year.   Curt (or someone) makes a long bar type that probably mounts ONLY to the frame rails (judging by your description).   It hangs fairly low which is one "downside" for aesthetics.  I like Tone's style better because it's less visible when installed.   However, I am fairly certain tongue weight is limited by that design.   I assume the cross rail isn't THAT strong?  
My other issue is I've installed dual exhaust.   I think it's installed slightly inboard from the OEM location and blocks my ability to install the Curt style hitch w/o redoing my exhaust.   That gets expensive AND tricky considering the hoops dual exhaust required by the exhaust shop.
Really, I think I'm limited to the Tone style (location).  I will only use it for a utility trailer to supplement OCCASIONAL storage/hauling limitations.  So, hopefully, the tongue-weight aspect isn't a problem.   
Please let me know if my reading has left any holes in my understanding.
FWIW, to those interested, I had more luck Googling "Vehicross Tone Hitch Image" than trying to find references/pictures using this site's search engine.   I believe a trip to the Curt hitch website will show you the other style hitch that I've seen referenced in a few threads.
Again, I assume the OP (Patrick) is looking to design a hybrid of the two?
				
			 
			
		 
			
				
			
			
				2001 Ebony VX and 1989 Custom 383 Corvette