> Or just let the float sensor bounce. It's underwater when it stops bouncing and is continuously in the up position.

Road grime, break dust, grease, grit, etc will contaminate the shaft and make it stick, potentially telling you that youre:

A) Never in water

Or

B) Always in 2.5" of water because the sensor is stuck.

I surrender my speedometer ceremony for the wade sensor. Instead of a motor sweeping the speedometer from 0 to 200 on startup, put the motor to sweep the wade sensor.