Baby Tandem axle trailer?
 

My friend is looking at a 20' SeaCraft MA "for sale" in Fla.

Check out this weird little Aluminum trailer. Anybody ever seen one like it? Very small Alum I-beam frame. Painted steel mast head too...

http://i1378.photobucket.com/albums/...psfqrtmaks.jpg

How about a pic of the rating sticker?

I've Seen some similar. Pretty sure it's an old Rolls Axle trailer.

Look close at the trailer weight capacity. Its not uncommon to have boats sitting on trailers that are too small for the boat. Works fine if the ramp is close to the house, but if you start driving longer distances, the trailers can come apart. Been there, done that with a Rolls trailer.

See them all the time. Probably rated 5000 lbs with 13 inch tires.
Perfect for a 20 SF (Your pick is not an MA)

Nice looking ride !

Back in 1975 (whew long time ago), I bought a 17' Mako with a small Float-on, single axle trailer. The trailer was built more for a small bass boat, than what I had on it. The beams were a little short for loading the boat without getting tow vehicle wet and I added a galvanized I-beam, that slipped in between the existing beams. I wanted to get a second axle for the trailer, but the owner of the company (Bill W.), would not sell an axle without turning in the old one. I managed to find another axle at a boat dealer's lot and I added it to the trailer.
I used that trailer for 7-8 years like that, until I bought my 18 SeaCraft. I then continued to use the trailer for a couple more years, before getting a single axle, heavier duty one.

According the user's ad on craigslist, it is a 1987 Seacraft 20'

And in the Broker's ad it is listed as a "1987 SeaCraft Master Angler 20". I realize the earlier model MA's had a raised cap, but wasn't sure if that feature was dropped by the 1987 model...