No Plan,
It sounds like our buildings are similar. My is 2200 square feet and I live in northeast Kansas. I have R-19 in the walls, R-50 in the ceiling, R-10 under the slab and perimeter, two doors, and 32' garage door with R-20. I also have radiant a floor.
In running the heat loss and heat gain calculation, here's how mine comes out.
Heat loss at 65 degree delta = 37,400 BTU/h
Heat gain at 28 degree delta = 22,100 BTU/h
In short I can easily cool my space with 2 tons (24,000 BTU/h).
One note, I would strongly urge you not to try and cool your space by running cold water though your slab! You'll need a squeegee, a wet vac, and a humidifier just to keep from having to swim to the door! Short version, the second your slab drops below the dew-point, you'll have a very, very wet shop!!
Best of luck,
Reflex