Testing part is right tip of Roa II wing. If you are able to print it you should have no problems to print also the rest of the plane.
It has to be printed as shell - 0% infill and no horizontal surfaces (thickness of the shell is one layer). Only this way you can achieve required weight of the plane.
Nozzle: 0.4 mm
Layer thickness: 0.19 mm
Use the default orientation (check the pictures below) and whatever printing material (read mode in how to print).
You can also check what printing settings are successfully using other users.
Your result should weight 7 g. The wall of the shell should be printed by one pass of printing head so that the shell is very thin.
You should be able to fit carbon tube with diameter of 2 mm and 3 mm into spar leading holes (bottom side of the part).
I recommend to try to cover testing part with covering film to test if material of your choice will not deform from ironing heat To find out more about covering check how to.