The heated O2 will not cause closed loop idle if you have an open loop idle calibration.
If you are using the engine in an off-road application there is no need to use an O2 sensor or to restrict yourself to 14.7:1 AFR.
I would suggest installing a check engine light, or at least a convenient connector where a light could be installed. You currently have no feedback to indicate a problem detected by the ecm. You also have no way to view "flash codes" which can be obtained with a simple jumper wire.