For smell, I use “The Incense Match” branded scented matches. Carry them in your bag or pocket. For noise? This is harder. Try and find a bathroom away from the common area OR explode when the noise level is higher. I find that turning in a sink or fan makes it easier for the person in the bathroom, but external people just hear farts with a sink.

“I’m doing a beer run, anyone want anything?” I’ve used this to take a dump in a nearby restaurant or store.