We're traveling to Costa Rica and tour suggested we take taxi to airport for our 12 noon flight. They said to allow 6 hours which means a 4 AM depart from Playa Carrillo. Is it safe to do this? Would taking a hotel in San Jose be advised? Is 6 hours enough time? I have safety concerns.
I've taken a taxi tour in Costa Rica that started around the same time, and was closer to the Nicaragua border, and had no trouble. So I wouldn't be concerned about safety, or at least no more than I would travelling the previous day. Make sure you organize it through your hotel and get them to pick you up there.
Your tour guide is going to have a much better idea of travelling time than we do, and six hours doesn't look grossly off either way.