A good question.
A local answer.

Check museum entry and ferry availability for both days before choosing. A late Friday arrival may leave too little time inside.

Check the ferry operator's current vehicle rules and fares, then ask your rental company for written permission and insurance terms.

A tour can simplify transport and interpretation; compare the actual stops and time on the island before booking.

Remember Salamanca Market has a specific trading day. If your ship calls on another day, choose a different waterfront activity.

If a public connection is awkward, compare a direct ride for the market visit with the cost of city parking.

Compare the landscapes, wildlife focus and full door-to-door duration of both cruises.

Keep your Richmond departure flexible and read the posted time limit; free parking is not guaranteed close to the stalls.

If not, compare an island tour or a separate rental arrangement. Confirm child seats and pickup details before paying.

If no same-day return works, consider an overnight stay or move Port Arthur to another date.

Choose Port Arthur if its history is the priority or Freycinet if you want landscapes and walking.

Plan the journey to the mainland ferry terminal and the transport you will use once on Bruny Island.

Check the live mountain forecast and road status shortly before departure; a city forecast alone cannot predict summit visibility.