Many stunters are built using free flight techniques,Look at the work Tom Morris has utilized in his kits .
they are essentially 742 ,000 pieces of 1/16 sheet and they live very well without weighing much at all.
A very good friend has stated to me several times ,You can build a plane with one tube of glue or you can build it with two or three tubes.
I have found that after obtaining the correct weight of balsa that the adhesive is the biggest weight culprit.
BTW four lb wood is not the correct wood in all cases.
I often use 6/7 lb wood for the LE sand TE sheeting.