Christian, how tall are you anyway? I only ask because I hear harpists who are 5’6″ saying they need to move the seat all the way back. I’m 6′ and very leggy and have never needed the seat the entire way back. The instructions I gave a couple years ago were before the Prius V had been tried more for harps, and the original poster wasn’t familiar with loading, so I included worst case scenario instructions for a regular Prius and how one could fit a concert grand.
I don’t think anybody has tried it with the seats all the way back. Hopefully you live close enough to a dealer to get a test drive out to your home. If I ever car shop again that’s what I will likely do, unless I get something obviously more than sufficient like a minivan. For now I’ve settled on ZipCar once again, realizing the hassles of renting a car once or twice a month are less than the hassles of owning full time. I’m fortunate to be able to use mass transit for my day-to-day non-harp needs.