Run the water in the sink while you poop - or even better, poop before you shower if you can, and just run the shower while pooping and then hop in when you're done. I also love Poo-Pourri for eradicating the olfactory evidence. They have manly scents as well. This is how it works.

When I lived in a similar situation, I reworked my shitting/showering schedule so that I pooped before the shower and ran the shower while I did so. That and the poo-pourri soothed my shit-shyness and upheld the illusion that my poop smells like cedar and lemons. XD