Goto the dirt road north of the base and look for this spot on the hillside. Where you can see a car ontop of the hill is where you want to be.
Edit: Can barely see the car in the pic. its basicly right in the middle of the pic just left of the pole.
Once up there use a sniper rifle to take a pot shot at a tank you see driving past.
This is the view from the spot on the mountain.
This should give you 1-2 stars and the tank should come out of the base and drive around the dirt road below so just wait till the star(s) are gone and then jump into your car and drive down there before they drive back into the base.
Block one of the tanks by stopping your car or walking infront of them and then just jack their tank. This will give you another star so just call lester and clear your wanted level or drive back up the hill in the tank until your clear.
Now you have a Tank.
NIce one for the pics, just where i thought it would be. i'm gonna try it now thanks =)
go to the fort, use the entrance dirt road to the left when you get there. you will see water towers and a mountain next to them. use the mountain as a perch to shoot the tanks once or even twice to get them to come out of the base. they start spawning at 11AM. once they are out of the gate and below you by the mountain, either wait for one to leave the tank and kill him, or just snipe him out. then call lester to get rid of stars, either wait for the rest to leave but dont look away coz they may despawn, or call lester and run down and take the empty one. then drive out of there before they can get you, hide across the street if you have more stars until theyre gone and bam youre free with a tank! hopefully i explained that well enough, im on my phone but let me know if you need more help. works every time for me though.
Nice one i'll try this tomorrow. i think i tried this once but must of been the wrong time coz no tanks spawned at all. cheers man! =)