I'm with the majority about keeping brakes. To go lower, I use 16" trailerwheels and made this modification to the hitch portion. I put a bolt so I have a lockout. I know they are free backing but the internals of my brake unit were bent, indicating a really hard stop. You can barely seethe bolt in pic2.
The trailer is now a welding trailer. It has a set of torches with 2 sets of bottles and soon to have the Hobart welder set in place. It was so beat up that they sold it dirt cheap (some time ago). Literally every corner was bent. I straightened and made it for setting a 788 box on....and then changed to welding trailer.
Note that if you think this AL tongue is 3"....it is not. I had to sandwich in 1-2 shim plates about 1/16" for the brake unit to fit snug on a 3" heavy tube. Don't think you will tighten it down without shims, because it will break the cast steel sides.