Thank you all for your feedback. This is what I hoped for. G2SS and the Resident Camp Standards were all I could find, too. Understanding National would want to comment on a specific request, and rightly remind the council they bear the liability anyway, I was looking for what other councils actually do.
I confess I am a NCS COPE director and NCS Climb/Rappel director and a regional COPE/Climbing inspector. Because of construction methods, I'll virtually guarantee no pioneering structure is going to pass a COPE inspection. At least not until we use class 1 utility poles and through-bolt lashings - neither of which is in the Pioneering MB book. G2SS merely recommends you protect over 6 feet like you would for COPE and sends you down the COPE/Climbing rabbit trail. belayer_StLouis is spot on regarding that.
I'm also a scoutmaster who wants to let my scouts have all the fun they can handle. A twist on a quote from above-mentioned respected colleague would be "Keep it Safe, Make it Fun." Che challenge is Safe vs Fun is an inverse curve. We can make all the fun we want if we ignore safety. If we make it safe beyond risk, there's no fun. In the days of our less-litigous youth, higher levels of risk were acceptable. Today it takes more training and knowledge to be able to identify, quantify, and mitigate the risks. At summer camp, the risk must be further mitgated due to the volumes of scouts versus leaders.
I wanted to make sure common sense was being relied upon instead of some rule or regulation I was unaware of. I had pretty much come up with the approach DeanRx spelled out. I heartily appreciate the outpouring of collective wisdom on this page. I will surely refer my tower-building scouter friend back to this forum.