The trip on the Spirit is not what it used to be, especially at this time of the year. The smaller and faster vessels are probably more practical but I preferred the fourteen hour trip on a bigger ship or the six hour dash on the Devil Cat.Tas will be on the cards as a last minute booking if Qld falls through. But I was reading the FAQs on the Spirit of Tasmania website. It says on the trip to Tas, you're basically confined to your room, but on the way back, you're allowed out. That's not very appealing.
The usual approach seems to be to send one sacrificial family member on the Spirit in order to drive the car and pick the rest of the family up from the airport,