I can't speak for the newer Jayco's, but I special ordered my 2002 Jayco 300FS with the additional insulation package. Again, I don't know about the later models, but the extra insulation was separated into the roof package and the sidewall package, but I don't know if that is the same as the "polar package". You can only get just so much insulation in a 2" wall, but the extra insulation in the walls of my 2002 is like an aluminum foil bubble wrap. Also for what it's worth I had them delete the window over the bed. We had a previous Jayco and always felt a draft from the window when cold weather camping. The window was only about a foot above the matress. You won't be disappointed in the quality of a Jayco.
2002 Jayco Eagle 300FSS Travel Trailer, 2005 Chevy 2500HD Crew Cab 4X4 w/Duramax, RDS 60 Gallon Toolbx/Tank Combo, Edge EZ, Boost Stick, Bilstein Shocks, Michelin 265 MS2, Isspro Pyrometer and Boost Gauges, ARE Topper, Honda EU3000