"Hitch mounted 30gallon barrel "
I hate to see that much weight unsupported there....
Does anyone know of small but high speed wheel / follower mounts... as with front castor wheels on big lawn mowers ? I think I have seen something close on tow truck attachments....
This would support some of that weight but not be a "trailer" in terms of backing up... it could pivot up and down on its frame which attaches into a receiver hitch.