10" wheels and a roller trailer on steep slips - I probably unhitch 1 launch in 10 (on a bad year!)
More usefully to you, My axle has a splayed tube as the jockey axle. take a 50mm tube, cut 2 slots about 1/2" apart each side of the diameter end, insert & splay.
All solid, no threads to gather water. Granted it's a PITA to change the inner tube, but
<touch wood> only needed to do that once in about 6 years.