Hope I'm adequately expressing my appreciation for everybody's input, even if I *am* pretty much shooting down all the suggestions!
Velobard- the foaming tip might make for a good pre-soak, getting the solution to cling better than it otherwise would.
Grimm- Isn't this nutty of me, trying to keep the poorly repainted roof of a minivan (which is already deeply marred) so nice when the guy who plans to buy it will never care?!?
Mr. Elusive & mikebai1990- Yeah, I like the idea of adding some ONR to my foamgun solution :xyxthumbs Sure wouldn't hurt anything IMO and added lubricity/encapsulation can only be good. I *am* a little leery of tinkering with something that's working so well, but it seems like a safe enough thing to try.
Wonder if the ONR is all that much better than QEW...I have the QEW and I'm really trying to cut down on the endless accumulation on detailing stuff.