Agree on a route the driver can accept
List the main destination, total driving time as estimated for that day, and the time the driver wants to be back. Ask which optional stops are realistic. A plan can look flexible to every passenger while quietly making one person responsible for all the extra time and work.
Give the passenger a real support role
The passenger can check directions before the next turn, read parking signs when stopped, and answer messages about arrival. If the driver needs to change the route, pull over in a suitable place before making decisions or using a phone. Avoid several passengers giving competing directions at once.
Keep a workable shorter day
If a late change would add a long detour, discuss it while parked. Keep a simpler route available. A plan that depends on the driver agreeing to every new request was never fully agreed.
If a final detour would add forty minutes when everyone is tired, decide whether to skip it, use another means of transport, or save it for another day. Update people waiting at home rather than making the driver try to recover time. The return trip still needs a willing, alert driver even after the planned activity ends.