I have been watching this thread with great interest Micro_Builder.
Like yourself I am also interested in Micro-HLG's and thought I would share
a few pics of a 20" projected span design im currently building.
I have modified a Free Flight HLG called "Bliss" with a new Y-Tail and altered fuselage.
Looks like my AUW will be 35g. I guess that translates to approx 8g/DM^2.
Which is a just a tad heavier than yours.
Im using a Vapor DSM2 Brick and a Bahoma 90mah Lipo.
All RC gear will be fully enclosed bar the Lipo which is flush with the side of the fuselage for easy replacement.
Here is a couple of pics.