I know the dilemma of not having exactly what you need available. Just wondered about the other carriage and knew you would have to modify. But I didn't know if it fit your needs. There is that hard to quantify point of where the cost/use balance is tipped one way or the other.

We work on the opposite ends of the scale you definitely being on the macro end of the scale. I've done some of that work when I worked on a rice farm but didn't like how they were always expecting me to work without proper tools. I did have a big old milk barn to work in, but that was a hassle too because of the troughs in the floor.

Do you have permits etc to contend with when you build your shop? Or are you in one of those areas where you can build whatever you want? I have a friend in Kentucky and he says you can do what you want where he is in the boonies.

I'm curious too why 2' above grade? Flooding? My biggest problem was it being hotter than Hades in the summer (100+) and cold fog for the winter. Was a farmer who had an earth sheltered above ground like bunker with doors on both ends and it was wonderful. Warmer in the winter and way cooler in the summer. Very cave like and dark to work in with the doors closed though.