Still a work in progress... 16 months later the concrete was FINALLY poured and spent the last 10 days watering the concrete 3-4 times a day. Should have read about the 'dam' method earlier.
The final size is 40x60 barn that I'll eventual close in. Down in Florida so humidity is the main issue. lucky enough to have a decent size solar array on the house that can power a barn, as well as a shop and the Airstreams AC when needed.
I'm going to section off a 20'x40' area at the back for some air conditioned space and running power there now (hopefully 150amps will be more than enough).
Certainly live and learn. I made it 20' too short for a 20' deep shop at the back and still fit the 325 in with room to maneuver. The only place I could put a 12' high roller door was the middle. That meant I needed more doors on both sides to have access once the bus is in there (32.5' long so no space to move other stuff in and out). I think the solution is to put a set of swings door on the outside (roller door won't fit - not high enough), and put the bus down there. Just not a fan of swing doors, especially for keeping rodents out... at least my level of carpentry
Fun project tho - looking forward to getting the walls on then getting serious about restoring the 325.