I've posted about this quite a lot; it drove me nuts for a while. There are now more booster options that work than when I first got mine, though. You're right - the Turbo is a horrible fit in the 3rd row. The Recaro ProRide works great, though. I don't think I was thrilled with the Monterey, but it was better than the TB. Basically, any booster that's thick works pretty well, it just needs to sit farther away from the vehicle seatback, which the Graco/Evenflo/Coscos don't do.
I'm trying to remember what all I've tried off the top of my head... the Frontier was good, the Nautilus in booster mode was all right. I don't think the Cybex worked, and I know for sure the old Parkway didn't, and I think the new one was better but I chose the ProRide instead. I feel like I'm forgetting one...
Anyway, I kept my harnessed kid back there (at least they put in tether anchors in all four rear seating positions!) and let the older kids have the 2nd row. I had a Recaro Start for Ricky in the 3rd row until he outgrew it; at the time it was the only thick booster I could find that was also tall enough for him. I also got a custom-made 86Y that I used for a while; it was great, but it's not really necessary now that there are more boosters.
So yeah, I'd say it's a good car for him, it just needs the right seats.
ETA: Buckling through the hatch isn't really that bad!