part of the point crucial Si-T is tryin to make is that he asked which car to put it on, not if he should try it at all...and most of the responses were telling him to buy a truck.
then again, money permitting, a truck would be better. but since he has neither the money, or the space, it's not an option.
towing 500lbs and having two fat kids in your car is not the same thing at all. the load on the engine will be increased, as there is more drag with a 500lb trailer when considering the additional axle, and the wind drag. also, tongue weight (albeit small with your intentions) will cause the front to have less traction. this will make emergency stops longer, and can cause real problems when accelerating/turning in rainy conditions.
finally, my opinion...since you only have your car and her car as choices, i'd say use your girl's coupe. factory ride height will help a little with the above problems...but not much. someone said you have no second gear on your hatch...that's no good, as you'll need all the low end gearing you can get with a little engine towing anything.