Road trip best practices

I'm tired of using cell phones in a road trip convoy, so I'm planning on picking up a GMRS license (everyone's related to me) and couple of packs of TD-H3s and handing one out to everyone. Given that we'd only be interested in talking to each other, my general idea was to pick a random channel (probably in the 1-7 range for max HT power), pick a random DCS tone (yes, I know they're not actually private), clone all the radios to the same setting, and lock the keypads.

Does this sound like a reasonable setup? Are there any considerations that I'm missing?

Most etiquette things I've found assume that someone's talking without a PL code — and probably over a repeater. What kind of etiquette is expected for a small cluster of simplex stations that's on the move?