Can you get brown?
I had often thought of running a thick Bead of silicone around the side and front edges of the roof (on top surface), which is what I think you want to do with the gutter.
However, your goal in parking is to level the RV so you will probably end up with small pools of water at any low spots on the roof. This could cause a leak around any roof protrusions.
Your drain openings may let the water out.
I guess if I tried this, and I could get brown, I would mount it above the current gutter on the side of the RV and put extensions at the ends.
What would it take to makes your current gutters work properly?
2014 40QBH Phaeton DP Cummins 380HP ISL, Freightliner XC, 2014 Jeep Trailhawk TOAD
Blue Ox Aventa tow bar, SMI Air Force One -South Orange County Ca.