I purchased a 5 x 8 trailer from Northern Tool and immediately Dad decided I needed a heavier axel and electric brakes since I will be towing with my MIni. So we replaced the axel and adjusted the placement than the original plans, put on electric brakes and purchased bigger tires than the original. Then dad decided I needed stabilizer jacks and so we added 4 scissor jacks, one for each corner of the trailer and to attach them a friend of my dad welded on a piece of channel to attach them.
Then we screwed on a base frame for the floor and we were stalled for about 3 weeks when dad decided we needed to order a larger piece of plywood so we ordered a 5 x 10 marine grade birch plywood from a woodworkers company in Charlotte, NC.