Matt,
The test pieces seem water tight - I will check some more as this is my first time using dope.
Re the joining/mating of the panels ;
I should get to that next week or the week after and will show it here.
Having attached the root faces with a minimum of PU (some people use excessive amounts of glue here and all it is is weight,a waste and useless) my plan is to first overlap the veil - as you have said there is some substance to it - actually the 0.3 with the 410 and dope is as hard as epoxy and 1/2oz glass ,maybe harder.
Anyway I've tested the veil on a lot of samples and even the 0.2oz supports the balsa enough that, with the veil on the tension side, the balsa always(100%) fails in compression. When tested the other way around, ie with the veil on the compression side the balsa always failed in tension on that side.
I will do a small overlap on the top wing, both sides, and on the bottom of the bottom wing. I will extend the overlap past the wing seat on the top side of the bottom wing.
This overlapping will simply continue any tension that is in a panel skin under load past centre to the other side.
Then I will use 0.6oz glass to back that - first a wide piece then a second narrow one. Wide of course will be relative to location. I think that will be sufficient. I will load the wing to check.

Yes I'm impressed with the tensile strength of the dope and intend to use it for the 'bandaging'. Again no abrupt change in load bearing characteristics by continuing through with the dope also.

Brian