I definitely can see your point, but if it were me I'd buy a vehicle that can be towed and pay the $$ to tow it. Never have liked the idea of renting a vehicle at the destination. If we had to do that, I would have preferred to stay with the truck and TT we had previously.
If we only needed a towed vehicle as rarely as you are indicating...If it was me, I would start to seriously question if a Motorhome and all the extra $$ it involves was the right choice for us or not. If your need for a towed vehicle is rare enough that you're considering paying to rent one separately...IMO a towable RV (TT or 5th wheel) and a tow vehicle starts to make a lot more sense.
Anyway, thats just MHO, and is probably worth exactly what you paid for it. :)