Generally, you're better off with the trailer slightly angled toward the tow vehicle anyway. If you load it at it's full 2000lb cap, it will drop a little bit anyway and you'll end up having the tongue too high if you level it unloaded.
Also, perfectly level might affect your max speed with an unevenly distributed load. Military trucks don't have to worry about that too much because they're much heavier than and don't drive as fast as civilian tow vehicles.
I've found the slight angle toward the tow vehicle helps keep the trailer from swaying the truck on civilian trailers at 70-75 mph. Of course, you could also make it perfectly level and balance the load toward the front of the trailer, but I've developed the habit of loading fast and not futzing around with weight distribution. I've done a lot of trailering in the last two years...
If you don't overload the trailer, you should have no problems with it not being perfectly level.
