If a 2A difference in current draw creates a problem, there are electrical management issues beyond the size of the units. Likewise, if the additional 2A load of the larger AC causes your supply voltage to drop to an unusable level, there are other problems, likely with the CG's service
Theoretically, you can over air-condition to the point where the unit is going to short cycle and not dehumidify. Given the poor insulation in RV, even in the "all season" models, that's not going to happen. I have marine customers with 4-5 AC units in a boat and not one has ever told me he wouldn't like to have more.