Getting out of the boat with a pelican case is no harder than getting out of a boat with a Jackson happy seat. I guess it all depends on your boats outfitting layout. I personally use my peli case because it provides better protection in the boat, as well as hiking around scaling rocks and such. Its all personal preference, but for me when it comes down to protecting a very pricey DSLR I am OK with the extra hassle. I love watershed products, I just prefer to have a hardshell protecting my camera.
As for a resolution for storing a camera in a watershed bag... here are a couple ideas that I have brainstormed.
1. Take a small cheap coleman camp pillow and lay the camera body and lense on one end of the pillow and fold it hamburger style. Then use like a 1-2' cam around the pillow to keep it wrapped. I just tried this and cinched down it is actually smaller than my peli case, but not very accessible. Another option would be to put the small amp pillow in a small stuff bag like a bivy stuff sack. The camera would be well padded, and be easily accessible, instead of having to undo a cam.
2. You could also use a thick hand towel or blanket, and line an inside of a small stuff sack and put your camera in there. Probably would go down a lot smaller than option 1. Here is an example with a t-shirt, sorry about the bad camera quality, was just brainstorming. I ended up using an old climbing skin stuff sack that also happens to be hydrophobic.
3. Use a GoPro haha