That is terrible and I'm sorry to hear about this Martyn. As a police officer here in Colorado I can tell you the laws do not favor the owner of rental property. You need to wait 30 days from the time the rental is due back and you need to send a certified letter to the crook prior to having it entered in the system as stolen! Browsing throught the posting above it appears that California has a similar law. This has to do with the fact that it is a breach of contract and can be construed as a civil matter in the first month. I don't agree at all with that. However I would still contact you local agency and try to report it stolen. A lot of officers do not not the 30 day law, so don't mention it, or do not care about that law and may report it anyway. I've done that myself in the past because it is sometimes the right thing to do. Good luck and I'll keep an eye out for it here in CO. On a side note. If someone sees an identical trailer with CO plates and being pulled by a silver Tacoma it's only me!!