Very strange rule! I am glad, that this is not the rule in FRA, AMS, CPH or other parts where we often change planes! The idea about renting a car seems as a good idea.

I will write to UA and ask, if they can check the bags in all the way. Is it up to UA or the departure airport (Guatemala)?

Btw. If the bags are checked in, how long time before departure does we have to be at the aiport?