1200GXman, the reason yours is running a little hot with only the thermo, is because it's being used the wrong way around. Those blades are cup shaped for a reason, and they only move air at the intended speed when the blades turn the right way around ie. when pulling air through they radiator, and not pushing it like you have it here. Just as a matter of fact, did you turn the polarity of the fan so that it would actually push the air, and not try to still pull it out opposite the air coming from the front when driving?.

My 4AGTE uses the exact same size fan, and a 1600 VW radiator, and it's never had heating problems, but my thermo sits on the inside with the blades pulling air.

You should look for a thermo fan that pushes, there are a few around, I think some BMW ones come with them...