Welcome to the site! Glad to see someone else close by. I am in Blackshear GA if you know where that is. I don't have an XLV, but will search up what I can. On the seat material, I would use some HDPE for the base. You can get flat sheets of it many places. Probably go with 1/2" at least depending on how big it is to keep it from bending. Is plastics.com has some. Farmtek has it, Grainger, several places you can find it. Just search HDPE sheets. A cutting board from Walmart is HDPE.

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