Scott,
In Terry Brox's page he is using something like 9g of glue, but I think that is per skin.
http://www.mackrc.net/patternwings2/index.htm
Honestly, is this a place to scrimp? If I double up on Terry's glue amounts, I will add 36g to my entire plane weight of 10+lb. But I will be sure of the bond and will not be risking a failure for the sake of 36g (1.27oz). Seems like a false economy to me...Just my $0.02 on it.
Mark