On 7/3/2015 12:03 PM, Dave, I can't do that wrote:
...
Helpful thoughts?

You decide G: my thought is that you need to consider the "net free
area" of the vents. In order to not choke the cooler, it needs a
certain area to vent through. The registers you linked to have
considerably less free area than their 10 x 12 size and together they
very probably have less than an open casement window.

How much does the cooler need and how much does each register have? If
you can't get an official number for the cooler, the total area of the
cooler delivery ducts would be good. Maybe Google could help you on the
register n-f-a.

Bob