Without spending an obscene amount of money for an oven is it possible to create one large enough for like a 16’ boat hull with high temps ranging 250-300 f?

If so what kind of things do I need? This area is not something I’m intimately familiar with.

Links are hard to provide when we are all based in different countries. Just look for fibreglass insulation for roof bats. Kingspan is a well known brand, personally I used Earthwool. You don't need the megaexpensive sheets of it, just look for the cheap rolls that typically have a layer of aluminium foil on one side.