I hear ya, it's a bit tough to fidget with a knob while you're also driving. [X(] Obviously you wouldn't want your pit person fidgeting with the knob (in all seriousness, it's actually not permitted in IMPBA for anyone else to touch the transmitter). However, many transmitters do have the ability to map the 3rd channel to a wheel that's conveniently located on the handle, so you can use your thumb to control it. This is perfect for those drivers who are all thumbs.
Moving on to the beer problem, you could get one of the devices in the attached photo. With this, you could down two beers hands free while you're driving.
And finally, I usually stay WOT (was thinking of another set of letters, but it'd probably get censored, so I'll save Ron and Matt the trouble) unless I'm hopelessly behind, or way out front.
If you're having cooling problems at full throttle, you might be too lean, are not getting enough water, or are running too hot a plug for the fuel/compression ratio, or some other cause.