Can a porta potty be serviced if it's locked inside a fenced yard?

Yes, a locked gate can still work for weekly service if you set up access before the first visit.

Most vacuum truck crews park on the street and run hose to the unit when the pad is only about 30 feet inside. That distance is usually fine for a service visit as long as the gate opens wide enough for the hose and nobody blocks the path with cars or lumber.

The standard fix is not a spare key on the truck. Call the dispatcher and put a gate code, lockbox combo, or temporary keypad pin on the route sheet. Some homeowners leave the gate unlocked only on the scheduled service morning. Others meet the driver once so they know the layout, then stick with the code after that. You do not need to be home every week if the access method is already on the ticket.

If the gate stays locked and nobody left a code, the driver will mark a missed service and move on. That leaves the holding tank full until the next open visit. Put the access plan in writing when you book the long-term rental so it does not get lost between office and truck.