Deffinately one long flat rail, two 10' flat boxes that can be configured to whatever shapes you feel, and a flat-down rail, or a-frame, or w/e... It might also be fun if you just take a really long 6" wide pvc tube, mount it on supports, and use it as a rail as well... they're hard to slide the whole way and they're fun too.
As for the run in, make one big ass ramp for the rails, and make it so that the ramp 'fans out' at the bottom, so that rather than just being a straight ramp, you can go down it on an angle as well so that you can hit one of the 3 jibs without having to turn after the ramp...
Go to your local hardware store, and buy some construction industrial grade lamps, some with stands and some without, and get a nice speaker system to pump tunes while you chil
Lastly, if you've got enough room for a sled tow-in jump, I'm guessing you miigggttt have a barn, in which case you should set up one of these... I've always always wanted to do this: