Best mattress topper for side sleepers?? My son’s dorm bed is ruining his sleep 😓

Helping our oldest pack for college, and seeing those dorm mattresses are straight-up tragic. They look like vinyl gym mats, and since my kid's a side sleeper, sleeping on that raw surface is going to trash his shoulders in a week.

I’m looking for the best mattress topper for side sleepers to make his dorm bed sleepable. I’m trying to decide if a 3-inch plush layer or a high-density foam combo is better for preventing joint pressure without making the bed feel like a hotbox.

Parents who’ve been here, what’s the best mattress topper for side sleepers that actually helped? Was it worth doing or a waste? And what’s that one thing you bought for your kid’s dorm that made the biggest difference in how they slept?