A good question.
A local answer.

If South Australia is a priority, choose one Adelaide-based region rather than squeezing Adelaide, Kangaroo Island and multiple wine regions into spare days.

Rundle Mall is useful for shopping, but check current evening opening hours and look beyond the mall for dinner.

Pack and check out the night before; allow a buffer for a missed pickup rather than planning to reach the airport at the last possible minute.

Read the operator's current stop list and dwell times; the tour works only if its village stops give you enough time to explore.

If a meal outside still fits, choose somewhere very close with a reliable return ride and a firm departure time.

Mix a few casual restaurant meals with market or supermarket supplies; this is often easier with children than booking every evening.

Compare a beach base with a central base by the number of city trips you plan during the stay.

Use Adelaide Metro's current journey planner for the bus to Hahndorf and note the last practical return service.

Check how you would reach wineries without driving; a tasting tour or booked transfer may be necessary from either base.

Pack enough feeds and nappies for a delay, plus a change of clothes for the baby and a caregiver in hand luggage.

Build in food and non-wine activities, and keep a sober driver for every tasting day.

A tour removes the designated-driver problem; self-driving gives more control if one person will not drink.