I think anything plugged into the lighter socket will be OK as they can just unplug it for the inspection, anything permanently wired in however won't be OK (officially).
It is open to interpretation but common sense isn't out of the window completely; PPF on the wings, bonnet and bumper is going to cause oil leaks......
When you said "stinger" I assumed you were a crim who'd just TWOCd a Porker and were on the run from the Rozzers. Quite why you were concerned about the warranty I wasn't sure...