Builders are always curious about what environment other builders are constructing their planes in. I'll attempt to provide some detail here to that effect. Having an unfinished space like this is a great opportunity to set up the "perfect" workshop for building an RV.

physcial
I will be doing all my construction in a 24' x 32' pole barn. It has a poured concrete floor, one access door, four windows, and two 8' garage doors. Ceiling height is 9'.
environmental
The space is not currently climate controlled. The walls are insulated with R-25 fiberglass and the ceiling will be R-60 poured fiberglass insulation.
power
The shop has a dedicated 100A feed off the load panel in the house. It has it's own 20-space 100A load panel as well with a main disconnect and plenty of separation designed into the circuits. There are something like twenty-five 20A wall outlets, six 20A ceiling outlets, and two 240V 50A wall outlets.
lighting
Primary lighting is provided by eight 128W T-8 flourescent fixtures on two circuits. This provides 1.33W/sq.ft. which seems adequate with the planned addition of spot lighting/work lights.
whats next
My rough plan is to pour the remaining insulation, install a furnace, epoxy the floor (maybe), install cabinets and counter tops, then start filling it with tools.