Sure.
Remove the fan from the heater assembly (under the hood).
When you get the fan out an look inside the heater plenum, mine was full of water in the bottom, right up to the bottom of the blend door.
I mopped out all the water with a rag, and was able to get in there with a drill and a drill bit (whatever you feel is appropriate), and drilled a hole in the bottom of that part of the plenum where the water was collecting.
I used about a 1/4" bit, something big enough that it wouldn't plug with gunk.
If you study the design, you will realize that the water is collecting on the air inlet side, so the hole size doesn't matter since it is on the atmosphere/suction side.
Fixed my rainwater flood on the passenger side floor.
I suppose there must be a crack in the air intake up top somewhere, but I think that requires removal of the whole heater box to get to (ick). Ford should have put a drain hole in there to begin with... Engineering fail.
Lee