OK, folks, maybe I should have been more clear.
I already own the Mazda--it is a Mazda 3, manual trans, front wheel drive. I am sure that there are many fantabulous vehicles out there, but this is the one I own. I don't want to buy another one.
I realize that towing four down is wonderful and scrumdiddlyumptious, but you can't tow this vehicle four down. That's true of 97% of vehicles out there, and you need a fair amount of modification to the vehicle, so it's not a panacea in any event.
I don't know what Class C I'll be using, but it will be 21-23 feet, probably along the lines of a late 90s Minnie Winnie. It doesn't really matter for the purposes of my question, as far as tow RATING goes--the car and dolly will be comfortably within the range of any such RV. A trailer will be heavier, but still within weight limits. The question, which I asked but hasn't been answered, is whether performance will be significantly degraded.
If the ground clearance issue forces me to tow the Mazda on a trailer, can a smaller Class C handle the load and the length?