Amp power wire routing

I tried to find an answer specific to the passenger side, but was unsuccessful in my searches.

I am planning on installing a powered sub under my rear seat and need to run 8 gauge power wire from the battery. I have seen that there is a grommet on the driver side that can be used, but can anyone shed some light on if there is one on the passenger side?

Since the battery is on the passenger side I figured going through the passenger side of the firewall, and down the passenger door sill, would be the simplest method to run power to the rear seats. In addition, that would prevent me from having to have the power wire running next to the RCAs to the powered sub.

Also, any suggestions on grounding points behind/under the rear seats? I’m sure I will find one when I get to installing everything, but figured it wouldn’t hurt to ask on here!