I know the ranch rules require me to stay on designated or established roads within the HMA. Is it okay to drive around a muddy spot or snow drift?
No, staying on the road is meant quite literally. If the road itself cannot be traveled without a noticeable risk of damaging the road or your vehicle, it is considered closed at that point. You will likely be cited if you drive off road other than to park immediately beside the road to allow other vehicles to pass.