This is very interesting to me to share something and learn something from your project.
I like your choice of low drag fram and there light weight components.
Sir, I have small experience of Quadplane and I would like to be a virtual team member of your team.
I request to all readers that please guide and correct me If need . . . Please
1) Can you think use of UBEC rather than BEC for pushar motor of plane mode. Becouse BEC loss more power as compair with UBEC.
If you could not find light weight ESC in UBEC at 12 A, than Can you think use of light weight only ESC just like you used for copter moter. And use separate only UBEC for servo and for PIX power purpose
Weight - 11g
2) Can you think use of 18650 lithium cell, 18650 has more energy as compair with lipo cell in same weight.
Some 18650 cell has high discharge capacity about 25A with 3000mah which is suitable for quadplane .
I tested those cell upto 20A , there is no any problem.
Or you can find original LG HG2 18650
3) All important information is available at
4) Normally roll and pitch PID value are same in Copter, but I experiences in quadplane roll and pitch PID valuve are not same with each other.
5 ) when you test copter mode of quadplane at first time, to avoid damage of wing and structure, I suggest first use damy flying wing on copter fram with same weight as original. After proper pid setup you can test original wing.
6) I used first QLoiter flight mode for take off height, than Qhover for fev second than FBWA.
In Qloiter mode plane will not slip in air as like in Qhover.
For landing - fbwa to qhover, after speed zero again Qloiter for land.
Hope you will properly update your project.