u/LLroomtempJ

I'm really struggling to remove this. I sprayed with wd40 and have been trying to get an 11" under-sink wrench to latch on, but I think the under-sink wrench I have, though standard size (according to the hardware store guys), is too small to grab onto the thing keeping the faucet in place.

Before I spend the $300-$1000 that a plumber is going to charge me for this, can anyone recommend what tool I should use to try to get this off?

It is in a tight space behind my kitchen sink