Any info on this in the owners' manual? damaging the rear undercarriage can be nasty and expensive. Like the rear bumper...to say nothing of the gas tank. Be careful. Maybe even consider a full car carrier trailer. How about another car? One that can be towed 4-down? I used a Chevvy HHR for quite a few years. Good car, good "toad"..and now only can buy them as used....maybe really inexpensive?
My first "toad" (in 2001) was a used 1996 Ford Contour...5 spd stick. Was a Mazda with a Ford badge. GREAT toad..., in 2007 went to Mazda to buy a new car to be used daily and as a toad....was told that one cannot tow a (newer) Mazda 4 down no matter what. That is why I did research and bought the HHR. No trailer, no dolly. Just 4 down. And....IMHO, that is best way to go. (My current 4-down "toad" is a 2011 Ford Ranger 4WD, automatic. )
g'luck!