Trailer axles have a normal camber built in. With the torsion axle
the thing to look at is the angle of the trailing arm. It is typically about 15 degrees down from horizontal. They will settle with age and the rubber will harden to the point that you will not have any real suspension and the tires
are the only thing absorbing the bumps. Typically they last about 20 years so before they need to be replaced.