I made a utility trailer for use behind my at then the JD317, and later used it on my 180 but now its mainly used on my Ford 1720. It is really over built, but then again I use what I have on hand that will do the job. It has a siderail frame of 3" x 4" angle of 3/8" thickness, and has 2 x 2" x 1/4" thick wall cross pieces on 12" centers joining the sideframe rails. The axles are set into a piece of 2 x 2 x 1/4 sq tube and rated at 4000 pound, and it does not have any springs. The floor in the trailer is made from a single sheet of 2025 T6 1/4" thick alauminum, and the sides are 3/16" thick 2024 T6 aluminum, that extend down overe the steel angle siderail and up 12" for sideboards. I have had a Ford 1972 IIRC cocuntry Estate or Squire or something or other station wagon setting on top of this trailer, and the station wagon was full of scrap engines and parts, and actually used it to haul it to the scrap yard to dispose of it. It worked fine when it was loaded, but with 10 ply tires, and no springs its not fun to tow on the open road empty. The trailer bed itself is only 4' woide by 80" long, and the wheels are under the bed. I had originally designed and made it to utilize hydraulics from the tractor to dump, and during the time I had the hydraulics operating on the 317 it worked fine, however I do not have hydraulics on my 1720 that are remotes. I used a scissors type arrangement with the cylinder mounted between the scissors frame to raise and lower the bed, as I had problems with ground clearance etc and length of the cylinder not working right when mounted like a JD cart is.
Since I did not have hydraulics on the Ford I have since utilized the hydraulic cylinder (after fooling with a hand pump unit for awhile) on a log lift platform on my log splitter. The hand pump units may develop sufficient pressures, but they lack in volume and was slow going, at least with the sized hydraulic cylinder I had used.