EXcitement wrote:...so if I peel back the carpet from the footwell during a heavy rain...would I be able to find the leak?
Maybe... but in my experience it's unlikely.
If you have something that can safely measure a 1-2mm gap.(I use a metal metric ruler that has a small piece of cork on it. The cork adds 2mm so if the edge fits but the cork doesn't were in good shape,but if it does the gap is excessive). It is possible (although uncommon) that the seal around the sunroof leaks more than the drains can handle. Checking for a 1mm gap in the roof seal will prove the alignment is within range. If the sunroof track looks clean the likelihood a clogged drain is pretty low.
There are not many things that will cause a leak on the drivers side. I would look at the connector for the door harness visually but not spend too much time there. It will most likely come from somewhere on the firewall.
Pulling the car back from the area around the dead pedal is pretty easy. You can fold it on itself to get to most of the area under the seat. I would think about doing that to assess the level of soaking.