Awesome build, love jets but not EDF. I have 2 black spinners I want to use on a prop powered SR-71.
I think some winglets on the wing tip would not only set off the aesthetics, but cantered out a little will help with some stability. Possibly increase your dihedral if possible would definitely help, but this may complicate the build a little with spars etc.
Good luck keep designing, building and flying!