I'm in the same boat with you, my shop use to be in an attached garage to my house, last September I moved and now I'm working out of a 30 x 50
wood framed building with metal walls, roof and roll up doors. I started noticing condensation right away and now that winter set in I think it's worse. I have crazy temperature swings here, it was 31 this morning and in in the high 60s this afternoon.
While not everything gets wet, my anvil and most everything else with flat steel like my drill presses have water on them some mornings.
to insulated this building is out of the question although I wish I had the roof spray foamed because when the Florida thunder storms roll thru the rain beating on that roof it's almost enough to have to wear hearing protection.
Currently I've just been spraying everything down with WD40 but honestly I think the only good use for that stuff is as a solvent, I don't like it.
I think I'm going to get some of that Boeshield.
I'm also going to get some Ballistol, I had some years ago and towards the end of the can of that stuff I threw it out, I couldn't stand the stench of that stuff, but I regress...I've got several muzzleloaders and currently have a .58 flintlock on order and while perusing the muzzleloader forums found that Ballistol is at the top of the ladder for cleaning muzzleloaders and black powder fouling.
Right now the only machine I cover is my rockwell tester and that's with a cloth paint drop cloth, I think I'll also start covering other things, probably with bed sheets like MTBob said. they should fit, look, and work just as well.