No Big Box store (Best Buy or similar) is going to want to touch an RV. Yes, they have a TV that will work but how do you expect them to mount it? Not going to happen. They will have EXACTLY ZERO idea of what is required for your RV to receive a satellite TV signal. Last time I checked the Best Buy type stores no longer sold Dish or DirecTV service or hardware anyway.
You need to go to Quartzsite, AZ this Winter or find a similar option which involves an RV dealer/installer of satellite TV services. If you plan to have these same folks modify your cabinetry for new TV's then you are going to need to get even more specific in your hunt.
Where are you located? Maybe someone can point you in the right direction for a place to drop those thousands of bucks.