I used to use really hot water, but for some reason, there would occasionally be a rupture in the abdominal area of the mouse.

You'll know when this happens because it's very unpleasant to look at, and it smells even worse. In fact, it's probably one of the most disgusting smells I've dealt with - ever.

I don't have the physics to back this up, but I speculated it was because it was thawing it too quickly.

Lately I've been having good success thawing at room temperature for about 1 hour, then dunking in really warm (not hot) water for a few minutes to warm it up. I don't even dry them off before offering to my snakes (they seem to prefer them soaking wet)...seems to cut several minutes off the time it takes to swallow.

I'm sure the above also applies to rates, you'd just need to adjust the room-temp thaw times as well as the warm-water soak times.