Wow thanks for all the replies. We will probably just do that. Fill up at home. Whats a few extra dollars for the security of our own water. Some people with our model trailer have had issues with the fresh water tank support bending, but we have travelled some distance with ours full with no issues so will likely just fill up at home. I emailed some parks nearby to see if they allowed filling up for a small fee. One park wanted $1 a gallon! I can fill it with Perrier for that price. We have a couple of 6 gallon jugs we will fill and throw in the back of the truck too. We are no where near our tow limit so weight not an issue.
Thanks again, wish us luck. First time infield camping at a Nascar race!!!!