Isn't the idea to go feet first, on your belly, so you can hinge at the waist and lower yourself down? I'm a bigger dude too, but when it comes to getting out quickly, efficiently, and safely it seems to me to let my gut drag and get scraped up than try to dive bomb head first. You were trying to avoid damaging the RV, which I appreciate, but if there's not a dinette or something there to start on your belly and push yourself out with your hands then get your behind on the edge and roll so your belly is on the window frame and your legs are dropping to the ground. Slow yourself as much as possible with your arms and upper body (via friction if you have to).
