DJ, do it yourself. Like Mellow Mike said, it is not that difficult if you just follow some simple steps. You have my number, call me anytime. What I did on my roof (not my trailer) would work perfect for you. That way you can add an additional panel, or two, if needed. It will really depend on your seasonal useasage and where you go and what you plan on AmpH demand. Believe me, there will be more AmpH demand than you might be planning. Bigfootford is right, use a template, or do like I did.
Also, be careful about advice of those people saying get a BIG panel. Remember snow load (parked/stored), tilting for Sun angle shadow (if more than one panel) and wind load will impact the cells by stressing them and the anchors in your roof.
I love my solar and the freedom it provides me, but economics, available area and battery space are a factor. For me? My 900w is not enough!