Instead of removing the battery, you could wrap the phone in foil.
Then if in court you can try to argue that for a tin foil hat like you, the actual tin foil cell phone protection isn't an indication of anything. And much less suspicious.
:-).
Not sure how it could be fully applied if in the police interrogation room having been apprehended in a dark alleyway with two large bin bags full of steaming skunk weed, freshly purchased off a Vietnamese gentleman insistent on counting every note of that £20000 just handed to him. Maybe that is just an edge case though.
Perhaps a better idea (and market opportunity) could be a 'walkers rucksack' that has a pocket for your cellphone. This pocket could be lined specifically to act as a Faraday Cage, explicitly so that you can have easy access to your phone for maps etc., yet be fairly certain that your day strolling in the hills will not be interrupted by the office, the wife and other cold callers. Such a bag could be plausibly denied in a way that plain old tin foil could not be.