I have a new

My problem....what is a clean way to either breach the firewall or connect it inside (behind the dash)
Installing a 25 Watt fire radio.
I can tap or lose a cigarette lighter,, they are 20A but would like to keep them and go battery direct. Looks like it requires a 36 inch drill bit or an installer with the flexibility of a lizard.
The Motorola came with fuse protected #10? wiring harness but must go from engine room to cab in direction of install....it's all made up. The zarking engine is in the way.
So..how do the pro's do it?
If nothing else this will spark a little conversation.
Thanks folks,
J'd