Posing as a potential buyer, call around to the local trucking companies, both majors and independents, and ask them if they have any wrecked trailers they want to sell for repair, parts or scrap. Go and look at them. If there is one missing a part of the landing gear, that's going to be pretty obvious! Plus, there'll be residue from your truck on the trailer, too, assuming they just off-loded the trailer and parked it. Nose around where you can, if the above idea isn't a player for you. It's going to take a little sleuthing, but it'll be worth the effort. If all else fails, the local radio news station or TV investigator-types eat this kind of story up! The guy who hit you isn't going to be able to keep this a secret, so people watching or listening may make the right move and call the station or the cops and speak up.
Can't hurt!
If you do find the toad and the cops won't do anything, eighteen slashed tires (plus his spare(s))on his rig will cost him about $250.00/each to replace, at least, so a $5K expense on his part will help your peace of mind!
Revenge is a dish best served cold.