Matt,
' I have a set of panels cut from 1/2 pound density foam (each core is 530 squares and weighs 2 ounces!.............. too bad I can't find foam like that every day) '

They don't make that here anymore. I used that in my Typhoon wings and I cored it out also - 1/16 light balsa and wrinkle cote - it was plenty strong.
If you core out the outer 40 to 50% of the span with a geodetic pattern and go with your inside veil method you ,even with the same sections , will get better snaps.
Initiating will be a lot easier due to the much reduced 'inertia' - it is reduced by a MULTIPLE of the 'missing' weight.
Stopping them is a similar story but this time momentum is in play as well as inertia - again a multiple of the weights in play.
We all too often forget about some of the fundamentals of the physics involved because we get our minds buried in other detail.

Yes 7" and 15" at the root - @ 10.5% - ( D Snow; please note - I had said 11% earlier)
Also it will be quite blunt at the root.
I am not putting enough chord in the LE capping strip to get a 'true' section at the root - we cut the cores this way - it will be rounded off some as a result.
I expect the slow flying characteristics to be quite good.

Brian