I'll be installing a multi-band Kenwood VHF-UHF and large CB in my 2003 Edge soon, as the warmer weather hits.
I do not know the best location to use on this ranger to run the wires through the firewall but on older years they had the computers on the passenger side so I would keep away from it.
My plan this time will be use a separate fused power wire to feed a small separate circuit panel just for the radios, probably a higher current Painless Circuit Boss setup.
The main power wire will have two segments, a red load and a black ground both fused for the total load of the panel and both run to the battery.
I add a piece of braid, sized for the two wires for a good fit, over the red/blk combo and then use heavy walled heat shrink over that, on the ends and where ever there may be a joint, I use a piece of heat shrink that has adhesive in it to seal the complete cable assembly.
On the battery end of the cable I leave enough braid hanging out to attach it to the body of the vehicle for a bleed off point, close to the battery but not attached to the battery.
The cable assy will run across the radiator support up the driver's side of the vehicle to the firewall and pushed through a rubber grommet but if necessary a hole can be drilled and grommeted to accept this wire.
Over Kill, that is my middle name, 10-ga wire for feed and ground, an additional ground wire from the radio chassis to the body, bonding of all doors, hood, tailpipe and tailgate to the body/frame of the vehicle, all extras but little to no noise problems in both the HAM Rigs and the CB, in a Ford no less.
Luck,
p.s. Stay away from any grommets that have a move part going through it.
This will cause chaffing of the wire, with in time, and shorts, bad grounds, etc.