First of all, congratulations on your new camper and welcome to the forum. As for your roof, keep it clean. I wash my roof every time I wash the camper (maybe once a month, give or take). I use Thetford RV Rubber Roof Cleaner & Conditioner. (Some people prefer other products, I've had good luck with that one.) Go up on the roof every spring and caulk any cracks you see around any of the roof penetrations or edges with Dicor self leveling lap sealant. You can pick that up at Camping World or any RV supply place. Also re-caulk your windows, doors, and any other openings on the sides with a good mildew resistant caulk. I agree with your RV tech that it is best to keep them in covered storage, but if you can't do that, doing what I mentioned above should keep your roof in good shape.
Mike in Tennessee
Former 2 time FR owner
2007 Crossroads Cruiser 30QB Fifth Wheel
2008 F-250 Lariat 4x4 6.4 Powerstroke
Firestone Ride-Rites w/cab control