I don't have any past experience to recommend a shop to you (I have always done such installations for myself) but Roadmaster has a dealer locator on their website. Roadmaster Inc
Any competent mechanic or experienced DIY should be able to do it, as long as they are the sort who will follow the written directions faithfully. There is rarely anything difficult about it and basic skills will suffice. You could order the parts from rvupgrades.com at much less than you will pay through a local dealer and then just pay someone by the hour for installation. If you have a local shop or even a handyman whom you trust, you might ask them. You can view and print the install instructions online at the various manufacturer's websites.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL