Traveling in a group— How do you handle it?

Most times traveling as a "group" of two vehicles is not convenient for us due to when we can actually leave the house after work. When we do travel together we try to maintain visual contact but it is understood that traffic happens. There is no need to be right behind the other guy. If we get to occasional visual contact the co-pilots will send a text making sure everything is good. If all is well the lead may drop a few MPH over the long run until the tail catches up some. If someone needs a comfort break communicating that fact is simple enough. "Next place you see to pull off for a potty break, take it."
Currently, we seldom travel more than four hours to a camping destination. And if we do the other couple needs to stop for fuel somewhere along the way. Might as well be half way so we can all stretch and get back on the road.