First as mentioned check the tire pressure then check the wheel bearings for proper adjustment.
Some friends had your problem and they took their Casita
to a small shop that made and serviced trailers for the farming community they were in.
uses the Dexter torque flex axle, newer ones incorporate the bolt on brackets, older ones were welded on.
Their trailer has the bolt on brackets and the shop was able to align it simply by using the play in the bolt holes. Then they tack welded it to keep it in position. It does not take very much out of alignment over many miles to wear like that.