Greetings!
First - Congratulations! Hope the baby gets delivered without a hitch...
Now, that #12 AWG issue...good question.
Because this brings up the CAPACITY as well as SHIELDING the truck may have from the RF this radio will produce.
So, that brings up ...
Mounting - how will you install that beast?
Meaning...
Grounds,
Bolted to the dash, Hump or Floor, or overhead console?
Coax, whether it's RG-8X or RG-58, or UG - XX <<Insert favorite 50 ohm line here...
Are you----
Going to mount the antenna using what or what antenna are you going to use?
Instance, Wilson 1000, 10K predator or A-99 (on a pickup? - ok well maybe not that big...) or 102" whip - Dual or single...
Because - distance to the battery and the distance to the antenna mount (or potential feedpoint if permanent mounts are used) will affect voltage drops, radiation in the cab (RF floating about) and losses in wiring runs as well as potential electrical failures depending on how the radio will be mounted (slip seating?) will affect #12 or #10 - because one is easier to use; #12 if used for frequent disconnects - while #10 gives you the assurance of capacity to carry the needed current for BOLT-ON and IN installs and less chance for failures - if properly fused.
Fused? Yes. Back at the battery, if possible - for if wire that big is run under carpet - a dead short will cause a lot of smoke and fill the cab up quickly to a point where you may be unable to pull over out of the traffic - let alone even be able to stop safely if the vehicles engine stalls due to the problem.
PREACHY=Off...
Ok had to say that - but #10 is a good choice for expansion too - but proper dress and feed thru insulation from the firewall as well as fusing - should make a good terminal attach point for inside the cab as needs arise.
Why antenna mentioned? Grounds, multi-point grounding may help in the DC realm but may wreak havoc with RF grounding and sending RF to where it belongs. The kind of grounding used will affect how the radio performs - best to use single point grounding at least for the case but feedpoint ground location can generate a ground-loop noise problem that would affect even the vehicles electronics...
Hope these hints help!
Regards!
:+> Andy <+: