Battery relocation wiring

I've had my battery in the truck for a few years now, but it isn't done 'correctly'. I've been disconnecting the FLD wire to get through tech at all the tracks, and then hoping no one randomly checks the cutoff switch in the staging lanes. I can see myself in the final round of Pro at the Divisional Finals getting random checked then DQ'd, so this year I'd like to fix the issue.

Can I take the large wire on the alternator (which I believe goes through the firewall on those junky bulkhead connectors which also need replaced) cut and solder a new wire to run back to the battery, then run another wire off the other side of the cutoff switch back to that same wire I cut to wherever it goes into the dash? It'd go from alt, through firewall, back to the switch, then wired off the other side of the switch, back up to the dash where the wire disappears to wherever? Or am I better off doing it with one of the smaller alternator wires?

I've read you can put a switch off the FLD wire, and shut it off in tech and on the track. I do not want to do this because at no point do I want to run just off the battery power. I go lots of rounds, and having a dying battery is like the devil.