Finding a Class A with bunk beds would be optimum for your needs. However, the bunks may not be a deal breaker. You will likely find plenty of used coaches in your price range. If you plan to tow a vehicle with the Class A check the towing capacity for the coach and the hitch.
Also remember that if $50K is all you can allocate you will likely have additional costs for possible tire replacement, minor repairs and equipping a vehicle for towing.
I hope you can find a nice coach so you can enjoy the RV lifestyle.