Often some of that empty bounce will be mitigated after a few good loads seat the springs a bit. That's a really nice trailer, I bet it will serve you well for the long haul.
Should I make sides out of 5/4 decking or 2x material? I want it to be strong but I also want to be able to remove and install fairly easily.
This reminds me I need to figure out some low sides for my new to me 14’er. I’m not sure there’s stale pockets either so will either have to weld some on (I’d rather not) or figure out alternative ideas. It’s a wooden deck and was my FIL’s he used to haul his Rino sxs with a hydraulic soil probe.
I hauled 5 yards of mulch last night and on the trip back (empty) it seemed a lot less bouncy. I'm hauling a tractor this weekend that hopefully will take the rest out. Overall, it tows great. New TBC in the truck and the trailer brakes work amazing together. Wish the truck has a little more grunt (4.6 24V), but I'm not in a hurry and won't be going far.