Busy season, handled.
A traveller books the spring trip on your website at 11pm. By morning they are in the CRM, tagged for that tour, and have had their welcome email.
Two weeks before departure, every traveller gets a reminder with the joining details. Questions come back into one inbox the whole team can see.
An instalment is three days late. A friendly reminder goes out by text, then email. You only step in if it is still unpaid a week later.
After the trip, a thank-you and a review request go out. The next trip is announced to everyone who showed interest.