Corian is fairly straight forward to work with. It can be cut and routered with a carbon tipped blade. It isn't a structual material and would need to have plywood laminated to it for the table /bed.
It is HEAVY. Beyond adding a lot of weight
to the trailer, it would be cumbersome to raise and lower the dinnette.
Best deals on Corian can be found at your local counter top installer. They usually end up with a huge bin of cut-offs, some as large as 3'x5'. The price is usually a quarter of the original.