In most cases, the correct response is to abandon stealth and simply kill the sucker.
Remember, we're dealing with a common guard here, whose DC 11 or so gets artificially (ie. by a system mechanic) inflated to DC 16. His hp will still remain very low.
In other words, if you're trying to both eat and have the cake (having trivial foes ruin the rogue's time in the spotlight), you're probably games mastering the wrong game.
A worthy adversary, on the other hand, might well have DC 16 by itself. So there's nothing wrong with the number.
Only with getting there by the DM arbitrarily saying "unlike every other militiaman, this one is so good, even a mid level rogue stands a good chance of ignoble failure".
You might have a good reason for this, and that's okay.
Just as long as you realize the check won't happen, since stealth is obviously the wrong approach here.