The RX4 is Trail Ready out of the box but if you plan on encountering any water, you'll need to use the included dielectric grease on the sensor and fan ports. Don't forget the motor sensor port!
Use the included dielectric grease on both sides of the sensor plug on the wire side. This will help keep the pins isolated from each other and prevent shorting through water. Apply grease to the sensor port on the RX4 and plug the sensor wire in.
Should you need the fan, try to avoid as much water as you can as the fan is not waterproof. Apply grease to the fan/data port, wire side of the fan plug and plug the fan into the RX4.