Evans waterless coolant

Run without a thermostat. That tells me right there that that supposedly "professional" company knows very little about how a cooling system works. ......and I THOUGHT I knew little. I would never in any way recommend running without a thermostat.

Also, if Evans is basically 100% antifreeze, that's some of the problem. 100% antifreeze doesn't have the cooling properties as a mix, or especially 100% water. It's a well known fact straight water is the dead best coolant to run in terms of shedding heat. The antifreeze added to it simply keeps it from boiling off in the summer, since water only has a boiling point of 212, it's certainly possible to boil over with 100% water.

So unless Evans has some "other" qualities added to make it a more efficient cooler than water, that in and of itself might be some of your problem. I'm sure they'd never tell you "THAT" though.