Doing a trip like that with 4 rigs without a plan, at least a loose one would be like herding frogs.
The plan sounds good on paper, but in reality could be a disaster.
I have a friend who traveled with 3 other rigs and what they did was say that they would meet up at a campground at the end of the day and everyone was on their own until then, that way everyone could hit the road when they were ready, travel the speed they wanted and see whatever sites they wanted to along the way. Sometimes they traveled together, sometimes not.
They all had Ham radios to keep in touch. The FRS radios are OK, but don't have a very good range, a CB is better. Cell phones work as long as you have coverage.
Good luck and I hope it works out. For me the planning would probably be more fun than the actual trip. LOL Though I have found that man plans and God laughs.