[bigeasy1]

It should be on the trailers "port side" near the tounge,but most likely has either worn off or missing.For the life of me,I can't figure out why these trailer companies make the cheezy aluminum foil serial number stickers.They never last.

I bought my boat and trailer in NY and had the same problem registering the trailer.
I live in Massachusetts,and My Insurance co,and State DMV both needed a serial number.

Simple solution,I went into my garage cut a piece of 1/8" aluminum into a 3x5" plate and took my letter and number stamps,and made up a long serial number.I came up with the number out of the blue.
I riveted it to the trailer frame.The DMV & Ins.co accepted it.

I said it was a 1985 Shoreline trailer(they're out of business)