Has anyone done this? I'd like to add some light into the cooking/dining area of the trailer as its quite dark there now. I just want to put in something like this: http://www.rvskylight.com/rvskylights.htm. Is the roof constructed similar to a house? ie; 16' joists? I'm thinking of just cutting the rubber roof top, and then cutting into the RV framing. Can't be that hard, can it?