I just this spring installed four toppers on our HC 343RL. So far not a sound from wind flapping and there have been a couple nasty thunderstorms. They cut drumming rain noise on the slide roof to none
The long topper - 13 feet over the LR will hold some water. There are a couple fixes that
may work. First 'fix'. Dometic makes a cradle that is supplied with toppers 16 feet and longer but can be used on shorter toppers> That cradle keeps the spring tube from flexing. I have one but haven't had a chance to install it yet.
Second 'fix'. Spring tension is NOT a delicate job but it can be a bit involved. You need to install a safety locking pin in the roller, each end, so when you pull the bracket off, the spring wont unwind violently, possible doing samage to your RV or worse, to you. Once that bracket is pulled loose, it's only a matter of carefully removing that safety pin, then adding a turn or two to the spring tension. Pull a copy of the Dometic installation instructions as a guide
More on spring tension - a topper is installed with cotter pins to hold the spring tension. To insert the fabric in the awning rail, you need to, without pulling the cotter pins, unroll a single turn, not two or three, then slide it in place. If the installer unrolled too many turns (ahem
) your spring tension will be too low to maintain a taunt fabric in a wind.
Curious as to how mleeder filled the 10 holes/topper that are now left where the brackets were and handling the different, unfaded color under those brackets.