You can get very creative when you paint the interior of your coach. We used to texture coat the interior walls of hotels and those same techniques can be used by anyone that wants to do the same in their MH.
After the wall is cleaned and properly prepared, it should be primed first. Then a solid background color can be applied to the wall. From Home Depot you can get an inexpensive hopper gun. In this gun you can add the texture colored paint, and using a small compressor you can spray on a contrasting texture coat to add depth and some interest to your wall surfaces.
This is not difficult and can be done by anyone with a little skill as long as you do not mind masking off the surrounding areas in the coach.