Air Conditioner

We have a 1991 Model 23.  It has a cabinet air conditioner in the cabinet next to the oven.  This is quite old and does not seem to work well.  We are on our way to FL this summer and want to replace it with the confidence that we will stay cool!  I see in the pictures that the newer 2720 have a roof air conditioner.  I believe this is the same floor layout as our Model 23.  Does anyone have one of these models with roof air?  If so, what kind of Air conditioner is it and how many btu's?  I wonder if trailmanor even uses the cabinet air conditioner any more.  We are wondering if we should try to ad the roof airconditioner to ours instead of another cabinet one.  Thanks for any imput.