Joseph, I've already got a list of equipment & prices from yesterday's searches, thanks :-) Fans would be good...LOL...
Paul, I'd be using the plywood platform, so maybe that would be okay. I've got a three-car garage in theory, but it's 2/3 full of a wooden sailboat and the rest is occupied with bikes, riding mower, tools, tools, tools. Plus that's way too big to afford to heat every day for a workout.
So I'm eyeballing my living room now.