Low dinette seats on Coachmen 213QB

I've replaced the foam in mine. The hardest part is deciding which foam to buy to get the firmness that you want. Foam is fairly expensive so I didn't want to do a lot of experimentation and it does soften a bit initially. I'd suggest Lux-R or Lux-HQ from these guys. Measure the foam thickness from the existing foam itself since it should be a little thicker than the cushion appears to be from the outside. If you have a hard time working the foam into the covering, you can wrap it up in a thin plastic painting drop cloth to get it to slide in more easily and the plastic can be pulled out after the foam is in place. You'll probably want to glue some batting on the foam too, here's a how-to. Looks like they have a Canadian website too. Foam cuts pretty easily with an electric kitchen carving knife or it cuts super slick on a bandsaw.