NOTE: You can do this with Fine Tuner now, and I have long ago stopped taking requests. This is a relic. Don't actually ask me to scale something down xD.
I made a script that scales entire aircraft. If you send me a link to your plane and a scale factor(x,y,z or just one number) and I will scale it and upload as a successor to your aircraft. Attached is a 0.1 scale of my jeep as an example.
https://www.simpleplanes.com/a/HRGPU9/KKPT3, 0.3333,0.3333, 0.3333