Hi guys. Sometimes there are moments when the four-wheel drive and locking rear differential can not do the job. Thinking hard to also install differential lock on the front axle. Or install a winch.
I would start easy and put the axle of your trailer all the way to the back, so a good portion of the weight rests on the tractor. Right now, you're just pulling dead weight. When you can put it on the tractor, it can help generate traction.
Innovative, good job making use of what you get can for parts. Is this a current upgrade you are making or one you did in the past?