Well that plans buggered then, can't use pen and paper cos its possible to to see what you write by the sheet of paper below on a pad, smoke signals are useless lets face it then we're done for already.
I've been in meeting rooms where every seat around the table had a desk pad in front of it. Not unusual to see of itself, a bit of leather or whatever inlaid into the table to give someone somewhere to write that isn't going to damage the fine veneer; these however were glass, and there would be a shredder by the door. If I remember correctly, at least one of the meeting rooms at Chatham House is outfitted like this.
I did some work in places with rooms like that. Lockers for your cell phones, computers, etc, escort only, with a body search and metal detector walk through going in
and out.
And even with that, various three letter agencies still manage to, um,
lose hacking tools, apparently on a regular basis.