Quickest thing is to use the backhoe to dig a pond and use the dirt for the rest of the track. Dig the biggest pond you can, because you will use lots of dirt. Study up on pond building before you get started so that you end up with something usable instead of an unsightly mudhole. BTDT. When you get done, you have dirt for the track and will soon have water source to water the track.
Tabletops are much safer and just as fun, but they take lots and lots of dirt. I have a 65 foot tabletop and a 60 foot double. The tabletop is a funner jump and more technical jump because of the way I built it. The takeoff and landing are basically the takeoff and landing from an SX triple, but I filled in the gaps with the takeoff extending about two feet above the surface of table, so don't believe that you have to have a double to get the adrenaline factor.
Pile the dirt up and use the skidloader and buckets on the tractor and front loader to move the dirt where you need it. Use the skidloader to shape the jumps. Backdragging will be the way you finish the jumps. Hardest part for you without a tracked vehicle will be packing the entire jump down. You will have to make jumps more rounded.
Take a bushog and mow the track into the field. Ride it to make sure the layout works and is fun without jumps. Then figure out where you need jumps to enhance the track. Leave yourself a highspeed straight or two and build some sweeping turns.
Go to
www.dirtwurx.com to read the track building tips. The whoop building lesson is spot on.
Tendancy is to make the jumps too steep. When you are on the equipment, the jumps don't seem as steep as they do when launching them on a bike.
I've found the blade on the back of the tractor to be of little use. You will need to get a disc to groom the track though. You should be able to find a good used 14 footer for around $1000 or you can get a smaller (7-8 foot) 3-point disc for less. It takes longer to groom with the smaller one and I think the bigger, heavier unit does a better job.