Wow Keith, I never thought of all the things you mentioned here.
I won't pretend I know any of that engineering. But I do know this. After my engine rebuild I put in Evans waterless coolant into the Meadowbrook, and I haven't looked back. Since there's no water in it, it doesn't corrode the radiator and engine. No need to flush and change it....EVER. And since the boiling point of this stuff is over 375 degrees (which is much much higher than your normal engine temp), its guaranteed to stay in liquid form, which means superior cooling and no overheating. It will never turn to steam (well, at least not in our cars LOL).
Its been in my car for a year now, and the radiator looks clean, and I've never had any "hot engine" issues. Does my car's temp increase on a super hot day going uphill? Yep. But only to about 195 degrees (up from the normal 180). Last summer we took it on a long trip when it was 96 degrees (the cowl vent didn't help us much in the cab ) and went up a long hill, and also got stuck in traffic for an idiotic amount of time...temp never exceeded about 195.
Yes, this stuff costs $45 a gallon, and you risk losing it all if you have a leak, but I don't worry about any of that. This product has been around for 20 years now, so its been proven. I'd certainly recommend it. One thing is for sure, your car is not going to boil over with this stuff in the cooling system. Might be something you'd want to consider.
Oh, btw, my car doesn't have a shroud, either. I don't remember any Mopar I've ever had having a shroud. And I've had a couple dozen different cars and trucks over the years. My big 68 Dodge D-700 (3 ton truck) with an industrial 413 is so well engineered that when its fully warmed up you can grab hold of the valve covers and not get burned (and hang on to them all day if you had to). The cooling system on that truck is a little different. Also has sodium filled exhaust valves, and the coolant lines run through the external oil pump to help keep the oil cool.
Anyway, guess I'm done rambling and I got my 2 cents in.