It's worth it. Obviously it won't be the same because you're just going up and down instead of like up down and forward when you're on an actual jump, but the motion is pretty much the same. Your legs aren't restricted by skis so it'll be easier to do rotations on a tramp but by practicing them you'll definitely feel more confident on snow. It'll be a bit different to go from tramp to snow but it'll be a lot safer to train on a tramp instead of just hucking it.
As for tramp parks, the only place I know of is skyzone and those tramps aren't bouncy enough and you'll get bitched at for doing doubles so it's not really a training place. I threw a triple front ( kinda dumb on my part but in my defense I competed gymnastics nationally so I knew what I was doing) and I'm no longer allowed in there haha. My best advice for finding a good tramp place is to find a gymnastics gym and find out if they do an open gym night. They'll have actual tramps made for that kind of stuff and foam pits to jump in to and that would be ideal, I think. Also, tumble traks are great. They're like a long trampoline kinda like a runway with a foam out at the end and you can run/ bounce down them so you get that forward motion of a jump on snow. Those would be at a gymnastics gym as well, where as a tramp park might not have them.