Unless there's some seriously hacked wiring in the dash, I'd be more likely to suspect the ignition switch itself - not the mechanical portion where the key goes, but the electronic switch further down the column closer to the firewall.
If you want to pull the dash, you have the idea pretty well solid but you don't need to remove the steering column, A pillars, hood and park brake release. You do need to drop the column by simply removing the two 15mm nuts.
There are three screws across the defrost vent area, not two. And there's one more on each side under the speaker grille.
When you get all that stuff loose, do the bolt under the dash at each end last; the dash support bracing is designed to allow tilting the dash forward about 45 degrees without removing it. The studs you see sticking out of either kick panel sheetmetal are the swivel points for it. It gives you pretty much the room you need to access the wiring to a reasonable degree; if it's not enough, then you can lift the dash up off the studs at that point and lay it down on the floor. Takes a bit more work to free it completely from the harness.