Umm...but your fixed fan is already the equivalent of a clutched fan that is engaged 24/7/365?

IMO your time would be better spent on checking other parts of the system. I'd check the thermostat for proper operation and pull the upper hose to peek inside the radiator neck for any trace of crud, before I'd mess with a known functioning engine fan.

But yeah, your dollars and sweat, you choose where you want to put it.