Lifeboat retreat
For this battle plan you need to initially get the covies to be mostly within the rockslide, from where they subsequently trickle out after you. Meanwhile you're in the lifeboat area, waiting to take them on.
Because the rocks are a fair distance off, you've got time to start whittling them down with a pistol or whatever. The situation is actually a bit like what you get with the far area defence, in the sense that you've got covies coming at you across a broad area, from multiple angles. But this time there's less of a gap that the Elites have to cross before they can start laying into you with their devilish plasma rifles, so you don't have as much time to take them down.
Also, things may be less intense because of the covies needing to find their way out of the rockslide. In fact, some could easily get stalled somewhere, and end up just standing around. If things work well though, the fighting can certainly be good.
There's a handy rock for cover, and also the lifeboat itself of course. You've got lots of supplies nearby too, including a pistol and sniper rifle.
Arranging the attack dynamic
My original recipe for arranging the desired covie attack was as follows. Drive up to the plateau around the left cliffside, then let the engine tick over for a while to give the enemy a bit of time to gravitate towards you. Then hit the accelerator and continue on around the cliffside, to 'retreat' to the lifeboat area.
However, whether that recipe works well enough with your particular save is another matter. But you get the basic idea I assume. You need to lure the covies into the rockslide, and then you exit to prepare for defence at the lifeboat area. You may need to experiment a little to see what works best for you. You might need to do a more careful job of luring the covies deep into the rockslide. It might help to pause in a few locations, for example.
Warthog at the back
Coming back from the plateau, one way I like to handle things is to drive past the lifeboat (it'll be on my left) and park right up against the wall. Then I'll advance forward a bit on foot, to a position where I can start taking down emerging enemies.
I often leave the chain-gunner in place (unusual for me), due to the difficulty of holding back the advancing Elites. But because the gunner is back against the wall, his work is more defensive than offensive. He'll usually only come into play if the enemy manages to start forcing me back.
Grenade mischief
There are several places where the enemy can emerge of course, and one little pleasure you can have is lobbing grenades to get them just as they show their faces. In particular you can watch out for the tell-tale green glow of a Jackal's plasma pistol, and lob a grenade even before you've seen him.