Yeah rent out an old warehouse build a sick setup charge admission (not too much though) = your very own jibyard.
realistically though try bungie cords (I assume you don't have a gynormous basement so a banshee bungie probably wouldn't work, but you also don't have to go that fast for a rail and box, especially if you've figured out that it's easier if they're down rails.
And if it doesn't work out, I'd definitely suggest you find your most adept carpenter friend and look up Corey Wrightsman's "Mt. Doom" (that's the main snowboarder in the Knifeshow vids if you didn't know) it's one well made drop-in and rails all in one. It'd have to be outside, but if you make it well/ semi nice looking I'd assume your parents wouldn't mind it that much being in the yard/driveway.