Let's see... Helmet, leathers(although I have not seen any made of leather for dirt biking), chest protector...
Oh, the tractor! Load your tires so you have the weight to get traction. I have a small Kubota, and lots of clay. For all around ripping, a Gannon roll-over scraper really lets you dig in. The teeth work independant of the scraper, so a second pass is needed to smooth. But, the scraper is built like a tank, and is heavy so it digs in to clay better.
I have a regular box scraper. It is lighter, and works for most stuff. But to really scarcify, the long teeth on the roll-over box along with the weight really dig in.
Get T&T too. That way, you can angle you turns and berms so you can turn and burn when you ride. Although the adjustability is there with the mechanical links, it is sooo fast to tweak as you go with Top and Tilt.
Another thing is to check Ebay. See if there is an old fire engine available in your area. Would work great for watering the track, especially were a regular water truck can not get clos(use a hose line or the deck gun).
Is your track already built? If not, you might get a dozer in to make the basic shape, and then finish with the Kubota. As much as I like regular tractors, it is really hard to beat a large skid steer or the hybrid tracked "all terrain loader" like the ASV-RC50, Cat-247, or Bobcat-T190 for this kind of earth moving.
Interestingly enough, for my times at Prairie City OHV, where they run the "Hangtown Classic" AMA-Pro races, I have never seen a tractor out or near the track. I have no idea how they maintain that track.