Ok, got back from my trip.

Before bed, I applied baby powder to the "problem area" and unzipped my sleeping bag completely, and wore it like a blanket. I slept great until around 3 or 4am, when I got cold.

Now faced with being cold, I zipped up my sleeping bag, and attempted to sleep. After sleeping briefly, I woke up to find my boxers literally soaked with sweat. I applied more baby powder, which helped me fall back asleep, but I'd wake up soon after with the same problem.

In the morning, I noticed even my arms and shoulders were sweaty

Any more tips? Thanks!