did you look at this?
https://discuss.ardupilot.org/t/dealing-with-vibrations-and-harmonics-a-competition/13619/17
some good info there…
do a high rate logging flight, and then the FFT, this will tell you whats going on.
if you have vibrations in the 80Hz range (FFT will tell you) you may need to add a wide base, very soft low frequency isolation under the system…
ONLY do this is the FFT check says you should.