since in 1.09b the .50 cal gunners still don't fire at the ka-50, i also think that this mission ist quite easy. also, with the reduced hearing capability of the ai even with the truerangeai-mod it is now very easy to completely surprise the base. (it was nearly impossible to surprise the first m163 in 1.08)
the only real threat, as stated by maddmatt, are the 2 m163's (of which i almost never saw the second be boarded by its crew btw). you cannot lock onto them (as on the strykers an) if they are not boarded, so in a surpise raid you have to rely on your rockets. as soon as the vehicle(s) are manned you can lock your vickr's onto them, but then it might be already to late because the 20mm vulcan packs quite a punch.
i edited the config of the ka-50 to crewvulnerable=1 to make the .50 cals fire on me in all missions, and *then* things get hairy. in the alligator mission even the trucks and the humvee from the convoy open fire at you, and you have to fly really low and use the terrain. quite fun imho. i wonder why bis does not fix this...