It is the 'something else' that would concern me.
I have used HydrX™ anti-fungal additive and PC-ICE non-conductive coolant with no ill effects. They are used in PC/CPU/Memory cooler applications, but probably not economical with your setup.
If you use the RV coolant, I would not use more than a 1 in 5 ratio and probably more like 1 in 20.
Do you have a coolant temp and flow interlock and/or alarm? (worth the investment)