Trailering my horse about 500 miles?

Hi in a few months I will be moving and taking my horse with me! I'm excited but also very nervous! I've never trailered that far before and I'm wondering how often I should stop and let her out so she can stretch her legs and get water, what kind of places can I stop at? I've made this trip by myself and I was able to do it all in one day, (leaving early in the morning and getting there late afternoon) so I'm hoping to go for the same thing with my mare, I can't afford to stay anywhere overnight. Is there anything else I should know? If you have any advice that would help me prepare I would be so grateful! Thank you!