My own experience over almost 40 years of riding and self-maintaining my BMWs, has been to use common sense. If I am in traffic that is running extremely slow on a warm to hot day, then you may need to pull over and let things cool down, or find another route. Basically, if when sitting on the bike and the heat from the cylinders is getting very uncomfortable for your shins, then it is getting too hot. Pulling over and stopping, may not be the best thing to do, as the heat will continue to build for a short while after shutdown. If you can, pull over to side of road and just putter along, keeping the air flow happening. Better yet, get out of the traffic and ride a different route till the bike cools down. Only takes a few minutes.
As to tuning carbs, I have never bothered with a fan. I have had stock bikes idling for up to 15 to 20 minutes with no ill effects. I say no ill effects because those same bikes are still on the road with a lot of mileage on them and most have never had any major work required. I figure that if I can get over 200,000 miles, or more, on an engine without a rebuild, then no real damage has been done by letting them idle like that.
Plus, if you take longer than 15-20 minutes to set carbs, then you have other issues involved. These bikes are so damn simple, you should be able to get the carbs pretty close prior to initial startup then it just takes some minor tweaking. But many people keep looking for a fix, where there isn't any real problem.