It is a pretty simple design. It is all 2"x2"x1/8" angle iron. There are two vertical pieces. I drilled a 3/4" hole in them. They connect through the gate bolt holes. I have not decided if I will use 3/4" screws or 3/4" hitch pins yet. Welded between them is a cross beam. I had to remove the light for the license plate. I'll snip those wires and terminate them since I won't be using a regular plate. The rollers are just sitting on the cross beam in this picture in the approximate locations where they will go. I was just checking the height to make sure the rollers about about 1/4" or so above the trailer bed. It is hard to see in the picture, but I did drill 1 1/8" holes in the crossbeam where it covers the brake lights. That was the largest step bit I had. Since there are also break lights on the side, it doesn't concern me. The bracket is held in place with the original gate bolts in this picture which are too long for the bracket.
After this picture was taken, I mounted the mini-license plate on the back of the wheel well. I drilled the holes to secure the rollers to the bracket. I also eased all the sharp edges on the bracket. I'm now in the process of painting the bracket.
I think I'm finished modifying the small trailer for now. In addition to installing the rollers, I bought a 12"x 1/2" threaded bar. While I wasn't real concerned about the gate assist spring harming the boat, I guess it might be possible if the angle was very steep. I happed to have a couple rubber stops laying around. Years ago I built my own bow press and used them as limb rests. After more parallel limbs and then crossbows came out, I ended up buying a good press that can handle all of them. So, I had disassembled that press I built and had the parts laying around. They just happened to be the perfect size to mount on the spring.
You can also see in the pic that I decided to use 3/4" pins instead of bolts to hold the bracket in place. I took the borrowed trailer back to my neighbor and loaded the boat on the new trailer. The only other small modification I made was to the PVC roller. At one particular lake I fish, the dam has some issues and they are keeping it low until repairs can be made. The ramp there is very long and steep. The PVC I'm using as a roller actually falls off the trailer into the water and I have to retrieve it before it gets too deep. I ran a rope through the PVC and tied it to both sides of the trailer with enough slack so it can roll up and down the trailer but not fall off.
I ran out of energy. I hope to put the new hitch on the big trailer tomorrow.
I got a second wind, and get the new adjustable combo hitch installed for the big equipment trailer:
I found a level spot in the driveway. I disconnected the trailer from the truck and tried to jack it up. I could not jack it up high enough to get it level. I had to put it on blocks, wind the jack back up, and then drop the leg. With the leg dropped further, I was then able to get the trailer level with the jack. I then pulled the old straight pintle hitch and inserted the adjustable drop upside down so I had rise instead of drop. I then loosely bolted on the combo hitch. I measured the height to the bottom of the ring and the height to the cradle of the combo hitch. Even with the combo hitch in the highest position, it was close, but not quite level.
The hitch itself worked beautifully. After I tightened up the bolts, I backed into the trailer and it centered the ball perfectly. When I cranked down the jack, the self-latch clicked into place. I took a test drive for about 2 miles around the block. It drove very nicely. The Kioti was loaded on it with the weight over the back axle still. The truck does not squat at all. Tomorrow, I'll take it to the farm and try moving the load around and unloading and see how it does.