As a NEMO type traveling from Austin via bus - we have a lights out and
G rated movies. If you can, section off boys from girls with an adult chaperone in between. We have a philosophy that we don't want to give even the slightest hint of impropriety and that holds true in any form of travel including bus. The team knows the rules set forth before they sign up for travel to competitions.
The team has played Catch Phrase and cards and I think they are planning the same this trip - they enjoy being together talking, reading, some even do homework
Your food plans sound good.
We carry water on the bus and they bring sodas, juice, etc.
I think your plan sounds excellent.
Jane
Edit: we also include other prior approved movies such as The Core - I don't know its rating but we went to see it as a group. Also - during the daylight hours they can change out seating but since most of your travel is at night, the separation is good and once the backpacks are opened, things just sort define spaces. And - there are Cracker Barrels along the way - we stopped at one of those on the way back after competition. Nice good meal for a tired bunch of folk. All the best!