Still looking, need tall interior, but half ton towable

Look at small lighter toyhaulers like the Jayco Octane Super Lites. Toyhaulers have better headroom, and the garage area can easily accommodate 3 bunks. The only problem with these Jayco flooplans is a corner bed. You would have to sleep in the open side, which means your wife would have to climb over you to get up.

Or you could rig up a longer bed in the garage, and let 2 of the kiddos have the corner bed. That might work pretty well.