Vic & all --
Some good ideas there.
Follow-up.
Project is well underway. I bought 2 sets of Perry-type scaffolds. For stacked use -- about 11.5' top height -- I added a set of 2x4 outriggers to the "back side" that put another set of feet about 30" out. It's solid on concrete, solid on rock, and solid on grass with some shimming under the locked wheels. Scrambling up and down the 6' single scaffold is now second nature -- at 11.5' things are pretty comfortable as well. For my 22' gabel peaks I did sit a 6' ladder atop the scaffolding. The scaffold surface is 30" x 72" so there is good clearance for all the ladder feet. It takes longer to paint those 22' peaks then I thought -- soffits, backside of fascia, etc --- but the two 22' peaks are done except for the fascia trim board (starting to kick myself for not doing that at the same time, even though it would have meant another brush and color of paint). Weather here is getting cool -- I'm trying to paint when the temps for at least 12 hours are > 40. Since I tend to paint noon to sunset, that means 40s through the night. Its' going to be a bit tougher now. I ran across another water damage spot, that I'll post elsewhere.
Some points on painting with a ladder on scaffolding -- it's easier to stand with the dominant hand side of the body away from the wall. So I'm right handed -- I found it easier to paint by climbing the ladder with my left hand against the wall and then reaching across, back, and out to paint with my right hand -- and as needed some with my left hand. That surprised me a little -- as I figured it would be better to paint with my hand closest to the wall - that turned out to be false.
Now onto figuring out how to attach the dormers. Cleats on the roof and a ladder might be the ticket for much of it. That one 12/12 roof dormer still presents some challenges -- but as one noted, it's right out the window of the bathroom.