If temps will be "near" freezing, you'll be fine using your on-board water systems and a hose to the park hydrant.
Whenever it's projected to dip below 32F overnight, make sure you have some fresh water in your tank, disconnect, drain, roll up and bring your water hose indoors to keep it warm for the morning. When it's above 32F again, go ahead and reconnect it.
Be real careful with your sewer hose as well - they can get a bit brittle in freezing weather and if they get frozen while they have waste water in them and you need to get back on the road - big problem for you. I suggest you dump your holding tanks before the freeze hits, and pack your hoses away.
That all said, when I'm parked somewhere longer term in freezing conditions, I disconnect the fresh water hose from the park hydrant, drain the water from it, leave it connected to the RV and leave it on the ground for quick reconnection to the hydrant when the sun is out and we're above freezing. I do something similar for the sewer hose when parked longer term in freezing conditions. I make sure tanks are closed and hose is completely empty. Leave it hooked up to the RV and the park sewer inlet. I wait until the sun is out and we're above freezing before dumping again.
The advice you've already received about using bottled water is also great advice. We carry a few gallons of filtered drinking water for drinking and cooking and also a few gallons of regular park water flushing the toilet and washing hands. You just never know when you may need both - in any weather.
Wishing you all the best.