Problem with powering the thermo is the chances of not running correct heat under normal conditions.

Having played around with this for a while, a couple of my thoughts and observations.

The first that comes to mind is although Benz has told us so many times that these traffic and low speed temps are to be expected and should cause us no concern, I have noted that they have changed the newer aux. fan system to include a
cut in for low speed fan that now is switched by both a/c pressure AND engine coolant....so that tells me something.
[ and something I am working on]

Second, note that they have switched to an electric fan in favor of viscous.
Remember , viscous is supposed to help out before aux., but when we need it the most [ stop light- high heat load], even
if it is locked up, it is only turning at idle speed [ Well, laady-daah]
And I'l be damned if I can tell if these things are slipping at low speed. [ Notice that if you are in a high temp situation at a stop and you go to N and give it a little Rs, the temp drops right down. Well, is that the viscous finally doing some good or are we just incresing coolant flow [ prob both]
As far as thermostat , we seem to be already up to factory spec full open and I have verified this , so a lower thermo is prob not going to help the overall condition [ which is leaning towards a border-line effecient system].
I am confident they are correct that these high running temps are OK, but I don't like them over 100....