You're going to need to find SOME way of pulling that top cola over and down, even just a little bit... if this was a photoperiod, I'd say do some HST - but that's not wise for an autoflower. If the stem is at all pliable, you'll have a better shot at doing something like that - if it's still, be VERY careful not to snap it... The only other thing I would suggest doing IN CONJUCTION with that is to find a way to raise your lights... I've had to balance my lights on top of the crossbars of the tent (tying the crossbars together so the light doesn't accidently slip off and fall on the plants)... but even doing this with your lights, you'll need to find a way to bend the cola down (or out and away) ...
Good luck! Great grow!