Your best bet is to use the grommet in the firewall, their is plenty of room and it is the most protected area for the penetration. I'm not sure it you have used any of the room there before to run wires Thur, but their is plenty of room for more. I have run about 25 circuits Thur that area, one a #2 amp feed and I can still get more Thur if needed.
It may look hard to you, but there is nothing to it. I like to use a piece of solid Ty-wire to push Thur and then tie the wires you need run Thur the hole to the Ty-wire, then just pull them Thur. Don't get lazy on this job, it is very easy. UN-screw the sill plates and kick plate on the drivers side, pull back the carpet where it goes up on the firewall and run your wires under it down across the door sills and to the rear. You may need to remove the rear b-pillar cover to gain access to the extreme rear of the cab, just try and route the wires out of the areas that might be steeped on. Also make sure the wires will not get nicked when the sill plates are screwed back down.
I have done this very procedure several times on both sides, it is quick and painless.