[JRTJH]

Most RV dealerships with a parts department will have both the "thin vinyl screw strip insert" and the heavier "snap-on trim cover" in stock. The thin stuff comes in two sizes, is about $5 for a 25 foot roll, the heavier trim cover comes in 8' strips and is about $6-7 a strip.

With either type, don't try to install it when it's cold. It'll be a "bear" to get in the aluminum molding, won't bend around corners well and will probably look "bad enough to redo it" once the weather warms up. I'd either wait till a warm spring day or warm it up with an overnight in a hot room and "rush your install job so it stays pliable while you're working with it.

With either type, you'll need to anchor the ends with a screw. Don't forget to cover the screw head with DICOR sealant so it won't leak.