You're certainly right about a full face helmet. I wear a flip up because it is much more convenient, especially since I wear glasses. I learned to keep it down when it's extremely hot. 115 Fahrenheit is like putting your face in a convection oven without a full face down and locked. Last October I rode under a power line with a bunch of large birds on it while my visor was up. One of them dropped a bomb that went just over the windshield, under the visor and around my glasses to hit me in the eye. I don't know how many points he got but it must have been a lot. Even with a Memphis Fats I can't count the number of times a rock or some other debris has bounced off my visor.

Also I agree, eat at the end of the day. Nothing like having to go when you're in a rain suit or out in the middle of nowhere.

Never tried compression shorts but I found a pair of slightly tight boxer briefs that go part way down the thigh help a lot.

Lastly, drink LOTS of water. Dehydration will sap your strength and disrupt your concentration.
I have a pretty good rain suit I worn quite a bit while on the road. I wouldn't call it a pleasure but it sure beats being wet. Invest in pair of rain boots like Fast Eddy sells and put them on before you put on the suit. Otherwise you get boots full of water and the water wicks up your trousers.

We all like to think of ourselves as rugged individualists. But when push comes to shove most of us are sheep who do what we are told. Worst of all, a lot of us become unpaid agents of whoever is controlling the agenda by enforcing the current dogma on the few rugged individualists who actually exist.