I did sign it over but due to his suspended registration priveledges it had to go into someone else's name and he did not want me to know who it was so the judge ordered me to sign the titles and just give them to him. I did and the truck was the only title he took to the BMV for transfer but not the trailer.
I am not a divorce lawyer, but it seems to me that that is where you should start with this. If the judge ordered you to sign over the vehicle and you did so, that should protect you from liability if you can prove you did so ... but it would seem that your divorce lawyer should be able to file a motion to compel your ex to file it. I think the registration privileges extend only to "motor vehicles" which a trailer is not.