Tesa 4965 is my go to double sided tape for really thin attachment to a chassis. Works well for plates, ESCs, transponders, tungsten cube weights for ballast, whatever. It holds well, best if everything is degreased and given a bit of full-bond time before stressed, but it'll work if you're in a hurry as well.

Sam Isaacs put me on to the stuff, and it's pretty much replaced all my other "servo tape" options used previously.