An L-shaped leg mounted in the 2" receiver and a snatch block will solve your problem. Will do everything you're wanting, is simple to make and is easily removable. I'd use 2" solid square stock for the leg though.
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View attachment 712063
Before I added the fairlead bracket to the bumper, my fairlead was mounted directly to the winch. My side pull rigging is a little different now due to the bracket but the same concept applies. My front shackles are farther in front of my winch than your shackles are. I used a shoulder lifting eye with a 1" diameter shank in the shackle mount opposite of the side I was pulling. A short piece of chain was used to center a snatch block in front of the drum. I didn't like side loading the shackle so the lifting eye was used.
You can create the same thing with the leg and block. The leg just serves as an attachment for the block and is laid horizontal and pointing opposite of the pull. Since the block is not fixed, it will allow for the range of movement you need for side pulls.
A step down in capacity...maybe a little. There are plenty of benefits to these winches that make up for that though. Been hashed out repeatedly already.
How so? I've had mine for about 2 years now and use it regularly. My M923 consistently weighs 27,300 due to everything I've added and everything that's stowed on the truck. A single line pull will drag my truck with all 4 rear wheels locked on flat ground. A 2 part line requires using a rear anchor to hold the truck in place because it will drag all 6 wheels. Some custom field chocks are in the works for this reason.
This summer I pulled 17 stumps in my back yard that ranged from 7" to 13" in diameter in roughly 3 hours. The only problem was keeping the truck in place. Not the first overload, failure or even drained batteries.
It was used heavily during the clean-up after the hurricane in Florida due to the massive amount of trees we lost in Georgia. It regularly pulls whole trees up the steep creek banks on our property so they can be attached directly to the truck and drug home for firewood.
I'm not sure I can ask anything more of mine and be disappointed. You have experience with these winches that suggests otherwise?