Yeah, do rear wheel weights first. Then, if the suitcase weights are too pricey, you could mount one or two pipes sticking out front and put barbell type weights on them.
I can't wait to see this thing pull some serious stuff. I bet that with the right weighting, you could pull that camper around the yard no problem. Or all your tractors stuck in gear. Hmm, Even drag a couple tractors sideways!
It may take some experimentation and practice... But with the right gear selection, right engine RPM and right weight distribution, you are going to be amazed at what that tractor can do. I think we will all be amazed!