Your pace will change with your experience and age.
Living in Indiana and loving the beach, we usually tend to do long hauls.
We one time towed an entire Saturday - ~800miles and while the destination was completely worthy that may take the joy of traveling really fast.
So what we learned is this:
1 - For us, more than 500 miles a day is pushing...
2 - Start early and make intervals shorter and shorter, for example, I tend to make the first stop after 3 hours, then the second in 2 1/2 hours after that then the 3rd stop 1 1/2 hour after that etc. so as you get tired, you have less to ride. The same for miles per day - 1st day more than the second day and if there is a 3rd day on it, this one should be the shortest.
3 - Track the next stop not the destination.... Seeing "10 hours 15 minutes to destination" is not as pleasant than "1hour and 15 minutes to destination.."
4 - Food has an incredible power over the mood of your "crew". Forget the diet when on the road and treat yourself and your crew with some good ol' delicious junk food
and that will make wonders boosting the mood of everybody...
5 - On long hauls, more important than speed is pace and stress control. I found that driving at 65mph is more stressful than driving at 62mph for me, so on long days I drive 62mph... I see other RVers run pass me and just 20 min later they pass me again and that repeats over and over because you can't hold the stress and need to stop more when driving fast so by the end, on long hauls, driving at 70mph or 62mph will likely get you at the destination at the same time.
6 - Keep your eyes on the road for safety but it helps to keep your mind on a project that you have: It helps to keep you awake and the time runs faster.... I have several sailboats schematics that I built in my mind this way
7 - Remember: It's about the journey, not only destination, so don't forget to notice the change of the landscaping, the sunrise and the sunset.... Those should be part of vacation too.