I think you did yourself a favor.
I used the foam gasket and had a leak.
I used dicor and had a leak.
I used dicor and ha a leak.
I used butyl tape and it's been fine ever since. After about a week of letting the tape quit oozing, covered the screws and seam with a dicor self leveling. The dicor cracked after a couple of years, but part of my annual routing is to paint the dicor seams with an rubber paint which fills in the cracks.
2015 Ram 3500 4x4 Crew Cab SRW 6.4 Hemi LB 3.73 (12.4 hand calc avg mpg after 92,000 miles with camper)
2004 Lance 815 (prev: 2004 FW 35'; 1994 TT 30'; Tents)