8-ball has given you some great ideas, but if some days those options don’t work, consider doing your PE in bed at night. Having some slight variation in your routine may enhance your PE efforts, anyway.
In a couple weeks, I’m going to be traveling overseas for a while, and complete privacy won’t always be possible. Part of the time I’ll have a roommate, or bunkmates on a train. But people won’t question my going to bed with a rice sock “for tight muscles.” Not everywhere I go will have a microwave, but that shouldn’t be a problem for you in a dorm setting. I’m used to doing wet jelqs, and I understand dry jelqs can create problems if you’re not watching what you’re doing. So I’ll have to monitor by “feel” rather than by “sight,” doing it “undercover” at night. The only trick is doing stretches and dry jelqs quietly enough so as not to be heard by a roommate.