I tried... and I tried... and I tried, about 10 times. I actually sneaked the best I could the last 5 but then gave up a day before the patch came out.
Got it right the first time after patch, playing very, very drunk and going Rambo mode, like so:
Run to hill where the three bushes (north of the camp) are overlooking the enemy armour, go to SW ledge of the hill to avoid exposure, wait for patrols to get near the Shilka in the West and destroy it (killing up to three enemy riflemen while doing it), pull back, reload, go to center of hill, RPG BMP near campfire, pull back, reload, move 20 to 40 meters east, pop up over the crest once more and RPG the last BMP.
Ignore the bullets whipping past you by now, run back to the extraction boat, gear up with a few more rockets (enemy patrols will lose you in the hill and remain there, milling around), avoid the hill when returning (enemy patrols are still looking for you around the spots you fired from) and instead take the pass into the camp from the north, the single guard placed there in the beginning of the scenario will not be there anymore since he is running around looking for you.
Destroy the remaining Shilka from 250 meters with the rockets you got from the boat. Run back to boat, extract.
It was very easy or I got very lucky, and when I set timer to run 4 x while running to the boat and back took all of 5 minutes.