Well they ship reptiles without heating their shipping box as long as the weather is good. And my BP was loose in my house for 2 months at room temperature in the upper 60s low 70s. and I am pretty sure the vendors just leave them in their deli cups overnight too its not like they bring along dozens and dozens of thermostats, heating elements and large enough enclosures for a temperature gradient. Safer for them to be too cool then too hot.
so personally as long as I wasn't picking up an incredibly sensitive species - i wouldn't sweat it.
I know that the reptile shows around here limit the amount of reptiles you bring into the show though, so depending on your check out time at the hotel on Sunday you might be toting all of Saturdays purchases back with you. Make sure you are allowed to bring them back into the show or ask the vendors you purchase from if they would hold till Sunday morning.
As for carrying all the critters. That's what my boyfriend and his big gorilla arms are for. We just use a snake bag. :p