It sounds like I found a near-term project. I'd be more than happy to get the work shop up to speed. It will allow me to bring soem tools and electrical equipment down that I can just leave there.
If we put in a false floor at the second step, how much head room is left? I'm 6 feet tall. I know that it's extra work, but putting in a few trap doors in the new floor will give us some extra storage space or even a place to hide a few things that we want to be very hard to find - you never know when you'll be boarded by Imperial Storm Troopers.
In addition to what you mentioned, we'll need to install some electrical outlets down there.
Finally, if we ever get a 250 VDC rectifier, it will probably have to live down there, too. There should be plenty of room to accommodate all of this stuff, though.