Stop in for a cup of coffee

What's the stupid scale rating if I try new dash wiring without removing the dash? Think I'd pull the interior so I can just lay down to work... Less of a yoga pose for hours
Every car is different but its not that hard to lower the steering column and remove the instrument panel. Then lay the harness out on the bench. Fix whatever is needed. Put it back in reverse. Look for ground connections the FSM may not mention. I found one of those. Actually two. Support hte harness however the factory did it.