2003 FLD120 Crawler hauler handling issue.

Back in 2021 I posted about issues I was having with handling, wandering, with my hauler camper setup. I spent a ton of time and money trying to solve the issue. Someone suggested to lower the air pressure in all the tires to closer match the weight of the load. This helped a lot and I drove fine for a year. It was time for new steers last year and when I replaced them the difference was night and day, that truck tracked like a laser. I was thrilled. Well this year it was time for new drives. The new drives brought a new problem. It tracked back and forth again, not horrible on flat roads, but horrible on grooved roads in construction, or right lane ruts. With the new steers I left the front pressure at 110 instead of the 90 I had been running, and it was fine, with the new drives I did the same raised it from 90 to 100. On this trip I lowered the drives to 90 then to 85, and it got better, but not great. I lowered the front back down to 90 and it did help a little. Flat smooth roads are fine, any ruts or road lines and it gets squirrely. The axle weights are Steer: 8360, Drive:12140, trailer: 5060.
The old drive tires had considerably less tread than the new ones, but the sidewalls were cracked.
Some of my buddies say I need a WD hitch for the camper, but I find it hard to believe that little bit of TW would be an issue on that truck.
Coming back from Moab yesterday I was seriously thinking of selling the rig.

Edit: From the cab, it doesn't look like the trailer is swaying at all. And for a year this setup ran fine.

This is the old thread...
"I bought a 2003 FDL120 single axle to flat bed for my Jeep, and tow a camper. It has had a wandering issue from the day I brought it home. It doesn't pull left or right, it just wanders. On right hand sweeps if you give it enough input to get it to go into a curve, it over shoots and you end up heading to the shoulder, and then it takes a lot of input to get it to start to come back to the center of the lane, and again it overshoots to the left. I thought it was something I'd learn, but after a few thousand miles It is clear it isn't me. I replaced the king pins because they did have some wear, I also replace the tie rod, and drag link. The steering gearbox seems to have minimal play, I don't think it is excessive. The rear (single axle) had shims on the passenger side pushing the axle forward on the passenger side. I removed them, now the axle is square to the frame. But it really didn't make a difference. The front axle looks to have 3.5 degrees of caster on both sides. I'm thinking it needs more caster at this point. I have called all around the Las Vegas area and can't find a place to get a good alignment, in fact I never found a shop that did caster. I'm looking for advice on this. I went yesterday and bought shims, (4) 2.5* figuring I'd take it to 5* and see if it helps. Then I saw an old thread on this forum about this issue. I didn't want to dredge up that old thread, so I made a new one."