...and now, a break from a lot of crawling around. I thought for a bit about just where I wanted what wires to go and how to route around existing trouble spots (eg: the exhaust) and think I've got it figured out. I grabbed an A2 wiring schematic, some thin rope, my label maker, a tape measure, and a paper & pencil for notes. Effectively, I've traced the existing wiring harness wherever possible and planned out the shortest paths I could to get to get from each sensor to the TCM & switched power. I think I've got a good idea now just exactly what lengths of wires I need to cut and should be able to form wire bundles so I know how much insulation to buy of what sizes... I'm not a fan of split or spiral loom, so that means I have to put the wire through all my looms before I crimp on connectors. This should prove an interesting challenge as I've never done one of this scale before...