Snowboard rail jam help!

Im looking into putting together a parking lot snowboard rail jam...dont know what goes in to planning one of them, so i could use all the help i can get! like best way to get snow, what to put under it, and the best way to build the drop in, or anything that you all have done to put together a parking lot snowboard rail jam

ive got access to the box, its about 18ft long which should be long enough for some steeez, it can be set up to go up down, or flat down, or up flat...i just think it may be kinda short...anyway any ideas please let me know!

I think that the liability would be a bigger problem than all of that stuff that you mentioned.

already have that issue taken care of...thanks though...