Whatever the reason, having them mounted to the transom eliminates those boats from a potential purchase. Definitely something to be aware of going forward.
2006 282 with 2016 F250's clean bottom 1.9mpg at 3400 24-26 mph. Dirty bottom it drops to 1.4mpg. Original engines were 3.3 F250's and did slightly less.
A & J Canvas in Vanceboro, NC is the place to go for your curtains.
For the cabin door, I would call GW customer service.
Bolsters could be gotten from local to you canvas shop.