It seems so. Since the level kit will do exactly what it's supposed to do (level you out) logic would dictate that if you load the back up and consequently drop the rear end, something must be done to prevent the back from squatting. Air bags would do the trick nicely. OR, if you don't mind a slight bit of rake, you could put the 1" blocks on the back. That way when you load it up, the effect of the sqaut goes more to levelling it back out. I sag only very slightly (if at all) pulling the rig in my sig pic. I use a W/D hitch. Hope this helps.
