Wow I didn't see this thread before, looks like you got lot of guys willing to come play already and help out. heck you get the wood and bet you could have a stand put up in a weekend, the track layout could be put in also in a weekend, Don't know how much room you had but you could have moved the track in a lil toward the pond and made a oval around that one, seeen some videos seem that what a lot people do.
mine was a oval but you could go straight at the first turn and go into the other part of the track i thought it was neat how i did it, but mine started as a oval and i wanted to make it bigger.
so your adding dirt to the whole track or your bringing in dirt for some jumps?