Yeah, we’re looking at ride-sharing with my father in law and his old Ford Ranger now as an option, the question there is keeping the bikes stable in the bed of the truck. Complex combinations of ropes look likely.
The Prius is pretty doable for road trips with small kids; we did a 500-mile e/w vacay at Easter, and nobody was uncomfortably cramped. We even had a strider and a scooter in the trunk for that trip, as well as all our clothes swim gear.
It’s when you staffing camping gear, or large things like bicycles that it becomes an issue. And obviously we’ll need more legroom as the kids get taller.