Most people towing a boat/trailer/car understand that having a flat tire will be a problem.
When you change the "full sized flat tire" and install the "under sized donut"...the donut is not rated to handle the hitch's tongue load/weight, of the boat/trailer/car. The donut is not rated to hold the weight of the engine, up front, either.
So, when not towing, it is never advisable to use the donut on the front of the car, because the weight of the engine. You are supposed to move a good "full sized tire" from the rear to the front and use the donut on the rear where there is less weight.
You should have a "full sized spare tire" available when towing and the ONLY hitch that allows a full sized spare to be stored is OEM # 08L92-STX-200
After market hitches are too "V" shaped, as compared to the OEM "U" shape, to fit a full sized tire.