Call some wedding planners and ask what is rented most in that industry, to get ideas.

Rent out nice folding chairs/tables. Or linens.

Your family sounds like assholes. Sorry about that mate. Maybe shift to working a job for someone else to support yourself for a while as you do your next project on the side.

I use yep.so for simple landing page / waiting page sites and I think it could work for you.

A proper smoke test site should look pretty built out I would say, and I’ve used https://lexingtonthemes.com/ for that recently