I don't believe your trailer has leaf springs. It should have torsion bars. Do you have stabilizer jacks on each corner? I can't believe the axle mounts would move enough to cause the squeaking unless they were not tightened on installation. The swivel points of the torsion arm may have some road grime that causes the squeaking.
But if the stabilizers are deployed properly, there shouldn't be much movement of the trailer.
I'm not sure, but there may be some movement between the hull and frame.
Knowledge: "A gift to be shared. A treasure to receive."