I was in the biz for 23 years, specifically 12V, you will need to investigate shops in your area that specialize in mobile A/V. Be VERY picky and a good shop will be VERY proud of there work and should have portfollios for you to look at. They should also ask you to bring in the coach and will "walk" the system changes or mods they they need to do. They will not be cheap, and dont jump at the first shop, unless you get a warm, fuzzy feeling. 12V shops that are good will have a loyal customer base that should be able to be contacted for a recomendation. When I was in the biz, we specialized in RV's. Mainly because I was an RVer, RV's are a special vehicle and require a special installer/shop to work on them. Take your time and investigate....good luck, hope this helps. I've been out of the scene for to long to recomend anyone.
Chuck, Ruth, with 4 legged Molly
2007 Tiffin Allegro 30DA
2011 Ranger, 1987 FLHTP