Ooh, you have an F-1850! Yes, big difference between that and a regular travel trailer.
GVWR is 2475...it's a light little guy. Pin/gooseneck weight is 550 lbs. All the rest of the specs on it are here:
Sunline Coach Owner's Club - Sunline Owner's Files - 1985 Sunline TT/TC/FW
I think your flatbed idea might be illegal in some states, I'm not sure. The only way I could see that idea working is if you had a full size, 8' wide trailer, and the frame were chopped off right at the axle(s) so that the gooseneck ball was right over the axle(s). Still, that idea has me concerned that the light trailer could skip around when taking corners.
What type of tow vehicle do you have? What are the specs on it?
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2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9473.8 (as of 6/18/21)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR