Get creative with the pallets, and bring some hammers and lots of nails - it's a million times better when the pallets are nailed down.  See if you can get some other obstacles to ride on, a big metal pipe, skips, car? etc etc.   Try and build a plateau, and stuff you can work your way up to.  I'll get some pics of the demo I did on Sunday (in Kranjska Gora - Slovenia).