Need help: Trying to change rear left taillight

[loth]

Hey guys, I'm trying to add clears to my 02 X5 3.0. I've got the sides done and the rear taillight.

The problem I have is that I cant loosen one of the nuts on the left taillight. I've got the other two off thanks to my ratchet. The last one is the furthest away and is hard to reach to due the nav and cd changer units.

I can get my ratchet on the nut but there's hardly any room to move the ratchet up and down. I've sprayed some lubricant on the nut but that doesn't seem to help, either.

Please help! I'd hate to have to pay the stealer $1,000 to get a nut loosened.