Metal Gear (NES) - Stealth Run - 5 Alerts / 0 Stuns

How much stealth can we squeeze out of the NES Port of Metal Gear?
Full Disclosure: Save states were used. Five of them. I might try a legitimate run in the future - but I would HATE to find out that a 4 Alert run is possible, after completing a near-perfect 5 Alert run.
Alerts:
00:27 Alert 1 - Dog Pack
00:32 Alert 2 - Lone Wolf
01:22 Alert 3 - Card Guards
10:25 Alert 4 - Camera
51:10 Alert 5 - Building 3
Details:
More than half of my runs end within five minutes trying to get past that first gas chamber.
I think most of the stealth strategies I use are pretty solid and repeatable. That said, I took an unnecessary gamble at the 19:33 mark by not waiting... The guard could have easily turned around.
I was a bit clumsy and impatient in boss battles - not that "damage taken" or "rations used" was the focus of this run. I could have waited at the 13:00 mark when fighting The Shotgunner, and I should have waited a little longer for the Machine Gun Kid's bullets to stop firing at 15:47. It's possible to skip the final Super Computer fight, but I figured that wouldn't be in the spirit of the game.
This run could also be considered somewhat of a "Pacifist Run" - with the only deaths being Coward Duck (who put hostages in danger) and Big Boss. That's assuming no one was in that Bulldozer... The Arnolds are androids so they don't count.
Oh wait! I accidentally left a plastic explosive on the four guards in the Super Computer room. But they become immortal when the timer starts, so we can rest calm knowing they are fine... I mean, assuming they escaped the explosion and OH GOD THEY'RE DEAD AREN'T THEY?!
Speaking of, I would have liked to have saved all the hostages - but saving two of them would have almost certainly resulted in an extra alert. For these two hostages (in Building 1, Level 3), you need to smash the Select button upon exiting their cells and pray that the menu comes up before an alarm goes off - so you can equip the cardboard box and narrowly escape.
In the end, I rescued 18 of the 24 hostages.