After cruise shore excursion in Miami-what to do with carry on bags?

[Bollycats]

When we get off our Carnival ship in Miami we want to do a cruise line shore excursion since our flight is after 4PM. I understand they keep your luggage on the bus and then transport you to the airport at the end of the tour. My question is what do you do with your carryon bag that has medications, electronics, passport, etc? Do you leave them on the bus in your seat or put them down below with the big bags? Does the bus stay air-conditioned when you're not on it? Just worried about possible theft and also medications getting warm in the South Florida heat. 

[Low Country Sandlapper]

I would be interested in knowing as well.

[indy71]

For the after-cruise ship excursions I’ve been on, you put your carryons in a small overhead bin or on the seat. The norm seems to be that the bus is locked while people are away. The driver might stay with the bus, but I’m not sure about that. I don’t know about the a/c