I’ve contemplated an SG build, as well.
I really like your multi-ply, neck-thru design with the tongue-in-groove construction. That is a really good concept.
But, if I did one, I’d make a few changes to the typical Gibson design. I’d move the output jack to the side and make some changes to the control layout. I may even build it as an HSS guitar. I may also move the pickup switch to the upper bout, similar to how I did to my Jackson.
Maybe I should get an SG husk and make some mods?
Or…maybe I should just keep practicing!