> I think the drains
are important in that they prevent too much water from
pooling between the gasket and the frame; if the car
is parked at enough of a slope the water might be able
to overflow under the gasket into the car if you've
only got one drain. Because the bottom edge of the
gasket covers the screws that hold the top of the
dashboard in place, I'm not sure you'd see water
leaking from between the gasket and frame since it
would have a direct path to the dashboard.

This is a very good point! I'm gonna poke a hole in my foil on that lower corner.
Thank you!