Cooler for dinghy seat

[Muaddib1116]

I have a 2018 Highfield CL310 and I'm thinking that I'd like to replace the seat with it's tattered storage cover/bag with a lightweight box that I can store things in and also sit on. The best thing I've been able to think of is to use a cooler, assuming I can find one that fits right.

But since I'm not really going to use it as a cooler, I don't really want the expense or extra weight of a high end roto-molded cooler. What I'm thinking is to try to find something like an Igloo or Coleman cooler with the right dimensions and reinforce the lid.

I know a there's a lot of examples of people injecting spray foams into their cheap, hollow cooler lids to increase their insulation, but would this add much structure to the lid? I'm a pretty big guy, and ideally, I'd like to be able to sit/step on the lid without damaging it. If there's some flex that's fine, but I'd like it to hold and spring back. Are there expanding foams that are designed for structure more than insulation?

[Brioche]

Why not glue a properly backed seat cushion to the top of the lid?

[Muaddib1116]

Well, even with a cushion, the lid will have to be able to support my weight.

[psk125]

Glue a piece of 3/4" plywood to the top on the outside, and you're done. A 3/4" board could also work, but might split more easily than the ply.

[CFS Klopas]

When I made a dinghy seat out of a 2x8, it wasn't nearly strong enough to support me. I had to screw in an L shaped steel slotted angle, which worked well. I've also sat on coolers that didn't collapse,so that might work too.

[Muaddib1116]

So I found that the Igloo Marine cooler sold by West Marine has a lid that is factory insulated, and they sell a snap on seat cover for it, so I guess that implies it is designed to be sat on. Also, Defender sells a product by Todd Marine that is designed to be a Dingy storage seat. I can't find any weight for it, and it has some strangely small dimensions for the internal storage. I think the question with either of these is if they will actually fit the tube/floor shape of my dinghy.