Pan temp is the right pace to watch it.
Heat will drive moisture out, even if it isn't 212. Not much moisture can get in to start with. Rear ends will run years, decades and most will never get over 200. They are more suseptable to getting actual water in them as well. I know modern ATF cooling packages that work real good to stay around 160 for normal driving and only when towing hard might get close to 200, and those run forever just fine.
It looks like your cooling package is working good. At this point leave it alone.
If you start seeing engine cooling issues (when working the convertor hard) I would suggest trying the coolers the other way. The oil to air first. That way you can shed heat before getting into the engine cooling system. But since you have a good cooling package now, just leave it alone.