Mrs Ned was out of town this weekend, so I got a huge amount done...
1st though, I forgot to list that last weekend I bought about $24 of wall-related stuff at the hardware store.  This weekend I bought about $100 more.
So here's what I got done.  I cut and installed the floors on the 2 platforms.  I also removed most of the 2" screws from the overhang ceiling and replaced them all with heavier 3" screws, each of which now has a washer on its head.  This is probably overkill, but I think it will support the ceiling much better.  I also had a large number of leftover decking screws, so I used them all to reinforce the wall in various spots.  I also caulked some of the edges & voids in the plywood.
I bought primer & paint at the hardware store, along with painting supplies.  A buddy of mine recommended I buy oil-based primer & oil-based barn paint...  it's cheap and he says it hardens to an enamel finish and reviews online are very good; the only downside is that it only comes in red and white.  Well, that kind of sucks so I was convinced that I was going to buy an expensive exterior paint from Sherwin Williams.  I stopped at Lowes before going there, and just on a whim checked out the barn paint.  It turns out that they now sell it in dark green and black, so dark green it is (barn paint is much cheaper - only $22/gallon vs $60-$80 a gallon at SW).  Yesterday I used a brush to paint the cutout, then rolled about 2/3 of the wall before I ran out of paint (400'-450' coverage my ass, I had only ~250' to cover but the wood soaked it up like a sponge).
For what it's worth, I hate painting and I'm bad at it.  I'm so OCD about perfection that as soon as one stray drop of paint goes where it isn't supposed to be, I go into "screw it" mode and just slap paint up semi-haphazardly.  I'm painting just the edges & front surface of the plywood for now, partly to save money & partly to allow the plywood to continue drying out.
So tonight I'm going to buy another gallon of primer & finish priming.  If I have any time left I may start the doing the cutout with the green paint.  The goal is to get it completed by the end of the week, then go backpacking for a week.  When I get back, I should be ready to put up the holds & start climbing.