I could never get the foam gaskets to work right on my SOF's hatches, it just required too much pressure to squish and never quite sealed.
I ended up switching to EDPM rubber weatherstripping, its the same stuff they make car door seals out of so it lasts forever. You can get it in the same aisle as the foam weatherstripping.
I got the D shaped stuff and put a strip on the hatch, and a second strip on the hatch ring, the two press together and it doesn't leak at all.

: You need to use closed-cell gasket material. Water will run right
: through open-cell material.