You may want to power-up the mini,then add your lens hood,and then add the filter so you can slowly go through the movements of your camera to check for clearance issues.
I think the ND is great for adding motion blur to video.I don't find much benefit to photography with my drones,other than blurring the movement of water with a stable drone and a strong filter, or getting rid of the "jumpyness" a fast shutter can add. The brightness of the scene will dictate the strength of the ND filter required.
A POLARIZED filter on the other hand is directionally dependent on the location of the sun for optimum results,but my results in capture have benefitted from their use.At times I prefer no polarizer and do the majority of my post starting with a "flat" photo.Some of my shots on the past could have been better wihhout a polarizer.