If you took a picture, go to a taxidermist and try to get a price estimate for a replica of them. (it wont be cheap) They'll either have to come up with your rack or pay the bill. If they refuse, take em to small claims court or file a claim on their liability insurance for their failure to exercise proper care custody and control.

If nothing else, they will be more careful in the future either not to steal or in preventing theft from others. That wont replace your rack but it may help other hunters whopatronize this idiot