LayoCaro, I recently did this in CA. I bought a trailer from someone who had purchased it from someone else without a title (and never registered it). For the DMV, I had to provide
1. A bill of sale
2. A DMV form (can't recall the exact #. I'm on the road now and can figure it out this weekend upon my return)
3. Verification of the VIN. This can be done at the DMV, of can be performed by a peace officer (documented on an additional DMV form)
A first, I thought the process would be difficult, but once the DMV understood my situation, it was quite quick and easy.