Depends how you mount it.
Bluetack and duct tape is temporary.
Drilling a hole is not temporary.
Compression clamps, suction mounts and heavy duty (hard plastic) velcro are not permanent.
I would hope that someone somewhere will make an approved, one size fits all compression fitting for skids.
CASA could be more proactive in affecting flight safety if they produced a guide for temporarily mounting of cameras inside a cabin;
1/ equipment should not interfere with compass or other instruments
2/ if items detach they should not be a threat to jamming of flight controls
3/ warning! the use of cameras can contribute to pilot distraction
4/ Video footage will be sought in accident investigations(!)
Mickjoebill