New A/C's cheaper from sites other than camping world...

i'm NO HVAC guy
but are these 'ducted' units

i would certainly check all the duct work connections/fittings for alignment and leaks or blockages, before spending money on new Units

if you replace them i would do 13.5k btu or even 15k btu in the living area
the front of an RV with Slides is harder to Cool, with that much surface exposed to the sun, the heat level is intense

No Slides ? that 11k btu should be cooling the area