I posted not long ago about inverting a subpanel. Now, a question about my ground/neutral wires in the MAIN panel.

My main has a shared ground/neutral bar, that is pretty crowded. When I run my 2-2-2-4 aluminum wire, it is gonna be kinda tight to get into the bar.

So, can I put in another ground bar and tie my ground and neutral wires to it? The real problem is getting that large 2 gauge wire into that small space on my existing ground/neutral bar. I thought of getting a collar strap, that goes on a ground bar, and putting that in for my wires. I would screw the collar strap right to my box, not the bar.

Is this OK? As all the other grounds/neutrals are bonded to the box, wouldn't this be the same as going to the ground/neutral bar?

I know that when I run to my subpanel, that my ground and neutral must be seperated, with the neutral on an isolated bar.

Thanks in advance!