I wouldn't do it. I have this swing out bike rack: Ridge Swing 4 - SportRack – The Way Outside with the Draw Tite hitch. I love it, but the van hangs low when it's loaded with bike, particularly since we typically take the bikes on vacation when the van is loaded down anyway. It's super easy to scape if you aren't careful. I think the box would be scaping constantly. I have AWD and there isn't an available airbag kit to fix this.
Brendan
Brendan