I'd put it up on jackstands and see if the wheel feels loose if you try to pull it in/out. In my mind, if the bearing went or the "vault" went, you wouldn't have any fluid left in there.
My money on smoke would be on a brake being stuck. Does this trailer have electronic or surge brakes? Any chance that the emergency/run-away cable was pulled? Once it's up on a jack you should be able to try and spin it and see if it feels like the brake is engaged.
Former owner of a 1987 Supra Saltare. Current owner of a Malibu 23LSV.