I'm in a similar situation. I just had my 2 year old Henschens checked because I noticed during my recent 2000 mile trip some excessive tire wear developing on the extreme outside tread of my curbside rear tire. The mfr specs obtained from these forums is:
camber +3/4 degree plus or minus 3/4 degree
toe +1/16" plus or minus 1/16"
My trailer has the following measurements:
Front axle camber left -7/8 degree, right -1/4 degree, side to side -5/8 degree
Front Axle toe left +5/32", right +7/32", total +3/8"
Rear axle camber left 0 degree, right -1/2 degree, side to side +1/2 degree
Rear axle toe left -1/4", right -1/4" total -1/2"
Despite the technician's best attempt to explain what it all means I don't think I totally understood. What he said is that the negative camber is excessive and that the toe is causing the tires to "plow" into the pavement and I guess it forms a V pattern causing the feathering on the outside portions of the tires. The curbside rear which is showing excessive wear is actually good in terms of camber but is wearing excessively because of the toe.
Nobody seems to want to adjust torsion axles. I'm told in my situation bending the tube will make it worse and in order to adjust the arms requires heat which will ruin the rubber. If I want good alignment I'll need to purchase a new pair of axles. Clearly the Henschens were out of alignment when manufactured as I have not run over or hit anything to cause them to go out. They only have 8,000 miles on them.
I told the technician that I'm not a full timer and average around 3,000-4,000 miles a year and I asked if my current alignment is unsafe and risking a tire to fail? I replace tires every 3-4 years so they would never wear down to the belts. The tech said no but that the plowing effect will generate additional heat which can contribute to a blowout. I feel my tires at every stop when traveling and while they can get very warm on a hot day from the pavement, they have never been too hot to touch and all feel the same. He suggested the cheaper way to go would be to have the curbside rear tire re-mounted and re-balanced from time to time to even out the wear. The other 3 tires are all wearing the same giving the impression only 1 wheel was out of alignment. He said $15 every now and then is alot cheaper than a new pair of axles, which may also be out of spec right from the mfr, in which case the mfr will fight a return and insist they were installed improperly. The technician did say that as the axles age and the trailer drops height, the negative camber will likely get worse. Heavier payload will also increase the negative camber.
I'm going to purchase new tires in the next year and continue to take 2000-3000 mile annual trips and monitor tire wear. I think I'll start rotating and remounting every 5000 miles also. If I get to a point where I'm wearing down tires after only 5,000 miles then I'll have to replace axles again...I was hoping I wouldn't have to worry about axles for 15-20 years and only went 2 years