Replying to Getting better with almost no skiing because of off season

I live in the midwest so no snow in the summer and there are no mountains to drive to that are close where theirs snow. The truth is this is my 2nd year of park skiing and my 1st doing rails. I progressed so much over this season its crazy. I went from not being able to hit a rail to doing any rail in the park with ease along with alot of tricks on and off of rails. I also have been hiting jumps some but i have been kind of intimidated to try any new flips. I can land fronts and backs along with spins like 3s 5s and 7s if its a good jump. I want to take my jump game to the next level along with rails but especially jumps because right now im around where I want to be for rails but not jumps. I improved so much but I want to get better. Every time I learn a new trick I i feel better then I ever have when learning something else alot of you probably know what im talking about tho. My question is what are ways to get better in the off season especially for what i want to do. I have a one rail summer setup im currently building and im going to ski camp at mt hood in June. Are there any other good ways to progress in the off season? DO summer setups help? Do people progress at camp alot?
Would lifting help or are there any sports that help you progress in the off season? Do Trampolines really help? Any other ideas would be great! I want to get really good, its not like I want to be pro or anything I just have the most fun when Im getting better!-Thanks and +1 for good answers!