When we had our Rockwood 2604, I took the spare and put it in the bed of the trk up against the from and used a cargo strap to secure it there. Yes it took up a LITTLE bed space but with it standing up the way I secured it, it wasn't an issue. That and it took almost 75lbs off the rear bumper tube of the trl.
2012 Winnebago "Journey To Insanity" 40U
2008 Dakota Sport 4x4
2004 Subaru Baja - DW's
2006 Honda Shadow Aero - TOAD for now.