This is still an issue and as said, you have to literally rush the objective. Best way is to follow the left hand trench. Turn left as you start and follow the trench you come to. Do not try and kill to many things and do NOT stray into the main road area.

You can complete this mission without even killing the enemies guarding the base.

So, trial and error with 30-40 crashes between my friend and I we found a way to get through this very frustrating bug.  

FIRST,  as soon as you are in the tank steer left off the road and drive through the buildings heading upwards.  Time may be a factor in the crash so TRY to keep moving and dispatch enemies as fast as you can, ignore turrets and just keep moving.  

SECOND,  as the buildings end and you come to where the road cuts across your path continue upwards veering slightly right as you go up. Your goal here should be to skirt across the road to come as close as possible to the trench that cuts  left to right through the map , avoiding the walkers, tanks, turrets, and troops farther off to the left. 

THIRD, navigate around the left end of said trench and head to the right. Literally hug the trench keeping the right side of your tank flush against it and proceed to drive through buildings taking out only the troops you need to, ignoring the tanks, walkers and turrets on the road above you. Let them shoot away, you just keep moving along the trench.

FOURTH,  as you continue right and the buildings end drive through the enemies there still hugging the trench till you come to the two tanks between three bunkers. Use your main gun to vaporize one of the bunkers directly in front of you and navigate through that opening past the tanks. This will trigger the final cut scene. When that happens click the "options" button asap to skip the scene  then hit the pad also as quickly as you can to teleport out. The game can still crash during and after the cut scene so it's important to end it and port out as fast as you're able... And that should get you through the level. 

Good luck! And no need to say tanks

I've tried at least 12 times but keeps crashing.  When's this likely to be fixed as cannot continue story

Same problem here