I also have the pressure relief valves, I will be doing some testing this weekend, I know the valves dumped @ 4000 & above, I'm expecting the pressure to be lower now with the lwp blocked off, I'll let you know

RD .... what was the result of plugging the drives?

Water under the valve covers and a raised level on the dipstick is two totally different problems. Like leaking headers,reversion,head gaskets,intake gaskets.
I dont run a stat and my valve covers are clean with no condensation. Cant say I have run in 45* water.
Knowing more about what # and temp would help.

get rid of those t/stats it will not work correctly and the water on the dip stick is cause of no oil temp it will do this with cold intake water but in the summer months it wont

How could you tell if any thing got fixed with no gauges ??????