I opted not to go this route myself, but just because it has
manufactured parts does not make "not homebuilt".

I do have a trailer that I bought from harborfreight as a kit. It is
licensed as a homebuilt trailer eventhough the manufacturer provides a
VIN plate and nice neat parts that are obviously prefabbed. I provided
the certificate that came with the trailer (that said "homemade
trailer" or something like that), and they went ahead and licensed it
as a home built trailer.

Also, I've licensed trailers as homebuilt when they were built from a
truck bed, or from parts of another trailer that had failed and
required siginificant (okay almost complete) rebuilding of everything
except the leafsprings.

As long as the #'s on your frame do not match up to a stolen or another
currently licensed trailer, they won't (and should not) question you.