Overheat is not that hard to manage, as long as you accept that you won't be running the engine flat-out all the time. I never use emergency power except in short bursts or, well, emegcencies
I use 1.35 Ata for the 109 as per the manual and work the prop to keep the RPM needle on or below the red triangle that marks the end of the normal range, but it won't break immediately if i push 1.42 Ata and 2700 RPM for a few seconds (never exceed RPM is 3000, so you have a big safe margin).
Similarly with the 110, i have mapped a key to switch to instrument panel view and it's very useful. It even over-rides your head-tracking device if you have one and it's easy to use: as long as you keep pressing it your view is locked to the instruments, the moment you release it you return your previous view.
On the 110, i use the RPM and Ata marked with the "d" letter on the instruments as my max continuous setting. The one marked with "30" is, evidently enough, power that you can use for 30 minutes (probably for the climb) and the one marked with "1" is usable for one minute. It's a bit more of a handful than the 109 because the values are a bit close to each other, but as long as you keep it in the range from a bit below "d" until midway to "30" you will not have any problems at all.
Absolute precision is not required because you might be a bit higher on the settings one moment and lower on the next so it evens out temperature-wise, plus altitude and airflow changes (airspeed helps cooling) further complicate things.
I just set my rads to full open for take-off, climb and any length of high-power scenario like combat. When i have the time to take a look, i watch the needles and fine tune it a bit. It's just about making a habit to check the needles periodically, just like you do with all your other instruments. You don't look at your compass in the middle of a dogfight and neither do you have to look at the temp gauges, as long as you've kept the engine running well up to that point and check the gauges whenever you make power changes that will stay that way for a long time (ie, if you just throttle up/down around your main setting in a fight it's no big deal, it's constant changes that matter most) it will be fine.
It's not necessary to worry about absolute precision. Of course, during the dive your RPMs will rise above the limit or when applying power you will go past the maximum continuous setting sometimes, but that will not kill the engine immediately. You still have to correct it, but it doesn't have to be an instantaneous correction.
Like i said before, listen to it because it talks to you. No matter if you like or dislike the sounds, the in-cockpit ones are very useful for tuning your engines.
Mind you, that's all for German injected engines. I tried flying the Hurricane and despite the easier constant speed propeller, i can't get it to run smooth no matter what...it always coughs and sputters, especially at altitude, but i think this has something to do with the way the mixture control is displayed.
In the real one, rich was back and lean was forward. In the game it works that way too in the virtual cockpit, but on the engine controls info window that shows the position of your sliders it seems to reverse from time to time. This confused me to the point that i didn't know what to press for lean and what for rich, so maybe that's why i couldn't run it smooth.