Hi Steve, and welcome to the forum.
East coast models are built in Indiana, and in 2009 the west coast plant opened in Oregon.
Aside from the distinct front cap designs, and some floor plan differences (as you've already found),
the basic construction standards (for walls/floors, framework, insulation factors, etc, etc) should
be the same for both east/west coast Cougar models. Construction differences, if any, would also
have to be noted in the Cougar travel trailer literature. Cold & snow isn't a factor
WHY the floor plan & front cap differences between the 2 factories??... well... who knows?!
I don't know, and I don't recall any of our members being given that specific answer from a dealer.
Keystone provides a map for the east/west dividing line:
http://www.keystonerv.com/cougar/#/floorplans
Yes, dealers 'can' order from either plant, 'IF' they choose to do so... they're not limited by Keystone.
And yes, there are some dealers along the east/west dividing line who carry both east/west models.
Also be aware that most RV manufacturers (including Keystone) establish 'perimeters' for their dealers
-sometimes 150-200 miles- so that there's no local/area competition for the same brand/lines. You'll
find that Cougar dealers are separated by a good distance.
http://www.keystonerv.com/find-a-dealer
Hope this helps, and good luck with your decision.
Terri, the Chevy co-pilot