...............any roofers out there..........

Kim (photos?) If I understand, you have a simple "lean to" unit up against the flat side of the trailer?

If so, I would not worry about "high and low" between the ribs of the lean-to. I'd simply get some flat flashing (or sheet metal from local shop) bent to as close to the angle between the two.


Screw the flashing right to the trailer, and the tops of a few of the ribs. Get say, 8" or so overlap on the trailer side so that any rain "splash" back under will run back out.