When the A/C is on, there is water draining onto my driver's side floorboard?

No one should be telling you the entire dash must be removed. Head under the hood to the passenger side of the firewall and look for a short rubber hose with a 90-degree bend in it hanging down a few inches. It will not have a round hole on the end. It will be formed into a slit. Squeeze that hose to open it up and see if anything comes out. If nothing of value falls out, there's a wire ring holding it to a plastic spout which is part of the drain pan under the evaporator. Squeeze that ring to allow the hose to be pulled off, then stick something like a pencil into the tube to dislodge whatever debris is stuck in there. Also clear anything that is lodged in the hose.

You may have to do this from underneath and crawling behind the right front tire.

I've been trying to find a drawing to show the tube of which I spoke, but apparently it's top secret. To add to the misery, in all the articles of instructions for replacing the AC evaporator or heater core in the housing behind the dash, no mention is made of removing that tube, which normally is a requirement.

AC systems are only expected to cool the air by roughly 20 degrees. The real comfort comes from them removing the humidity from the air. That is accomplished by condensing that moisture on the cold evaporator. That water has to go somewhere, and no one wants that to be on your feet. On all car and truck models, it drips onto a drain pan, then through the rubber tube and onto the ground close to the right front tire and makes a puddle on the ground. This is the first time I've never found a reference to that drain tube, but there has to be something there to clean out.

Please let me know what you find.

Dandy. Remember, there is going to be water condensing in the dash, and it has to go somewhere. I'll be here waiting to learn what you find.