I would reccomend axle capacity not much more than your gvwr plus mybe 10%-20%. More capacity means less deflection for a given load resulting in more road shock transmitted to the trailer.
Now if you were talking beam axles with leaf springs, OK, but not with torsion axles.
I put 2 5000# axles on my 9100# Classic 30. I got EZLube axles and mounted Kodiak 12” disc brakes behind 16” wheels. I don’t think they would have fit with 15” wheels.
“You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins