I had a vinyl (pleather) Russell with the same issue. I compared it to a stock seat that I had laying around and the part number on the pan was the same. I would think that BMW would change the part number if the pan shape changed. Maybe you should compare the part numbers on your RM to the one on your stock seat.
I never did figure out why one seat had a bigger gap than the other but the pleather on my seat in perfect shape and I doubt it was strong enough to bend the pan - I could barely bend it with my hands.
2005 GS1150 Adventure - Range Rover, 2002 DR650 SE - Land Rover
"Not all who wander are lost" - JRR Tolkien