We're happy at about 300 - 350 tops. We have a trip planned early summer to CO and to make everything work, we have to push a day or two to about 375, but then have 5 days to enjoy our BFFs in Durango...they're coming from CA. On our yearly trek to FL for baseball, our DS#1 has a fist full of health issues and has to get out and move around every couple of hours, so it's forever and a day to get there.
At the risk of repeating myself, which I've been known to do, the DWs need to learn to drive towing the trailer. #1 reason is in case of illness, which is how I learned OJT. #2 is that if you need to squeeze in a few extra miles, you have 2 drivers to swap off. DH has decided that I do a darned good job and he'll just sit in the passenger seat and let me to it....he's wrong..as usual, but I do enjoy towing and feel 100% safer know that if push comes to shove I'm ready. DHs, just sit quietly and let her get a feel for it. Happy camping.