I wonder if the low nose weight is related to the centred point of balance in the car - no engine out the front to keep the front wheels on the ground could cause steering problems in emergency situations with a big lever out the back?
I'm sure it's not to do with that balance. There's plenty of weight ahead of the tow point. The issue will be to do with the leverage on the fitment. Going over even moderate bumps will put a tremendous twisting force on any rear cross-member if there is a high weight on tow bar. Even an overweight trailer isn't going to come close... IMHO of course!