On my trailer, I bought a 2" square receive hitch, for a few bucks, at the local farm supply. I then had a guy weld up some plate, to mount the winch on. I'm not overly pleased with it, but some modifications will get it right. The winch stays on the plate, in the toolbox. On the bottom of the plate is some heavy duty 2" square tube. There is a hole, for a standard pin.
On the trailer, between the A frame that is on front, that goes to the coupler, there is a large piece of C channel that goes from the coupler to the front frame of the trailer. It holds the jack and has a reinforcement from the jack to the inside of one side of the A frame.
I had a 6X2 heavy steel tube (can go measure the thickness, if someone is interested) welded, vertically, all around the bottom of the tube, which is on top of the center C channel. It is then welded all the way to the top of the trailer (where the deck is), along the front of the frame. The front bar was cut and welded to the 6X2. The purchases 2" receiver is then welded on top of the 6X2. I wanted the hole horizontal, but the guy put it vertical.
To date, I've used the winch, a Warn 9,000 lb with a 135 ft line, several times and the mount hasn't had an issue. The only issue I've had is the plate the winch mount on wasn't made to hold the fairlead (part of my dissatisfaction) and the cable tends to want to rub the side.
Here's some pictures:
The trailer gets pulled on gravel a lot, destroys the nice paint.
The mount, which we wanted to take up as little of the deck space, as possible:
It's welded everywhere it touched the trailer:
To the right side, is one of the three heavy duty D-ring, that flips up (as shown). This one is to connect the hook to, for using the ****** block:
This is the inside of the toolbox, where we keep the hitch, the winch, the large winch battery (charges while you drive), ****** block, and all the ratchet straps, chains, tie downs, etc. A friend and I split the costs of the trailer and other tools. The trailer is his, the toolbox, winch, and most of the straps are mine. We then split the expenses, as they come.