Thermostat idea...

I certain, buried in these posts somewhere, is discussion as to a thermostat solution for the ever-popular problems we (and especially those with E500s) tend to have with cars running hot in traffic, losing power, etc etc. However, I couldn't find it, so I'll hopefully hear from a few of you.

To those 'in the know': is there available an aftermarket thermostat with a lower yield for activating the auxiliary cooling fans and clutch-driven fan? I'm under the impression that these devices are all switched on by the thermo, which doesn't even kick mine on until I'm halfway between 100 degrees and "uh-oh". They work very well once on - why not get them to spin at a lower temp before things get really heated?