As you are starting form New York the coldest part of your trip really will be the leg south .May I suggest that timing is everything to being comfortable, as I live at roughly the same latitude and have the same dilemma.You on the east coast actually have it a bit milder so all you need to do is have the bike ready and loaded and wait for a spell of dry and above freezing, and race south on the Interstsate when it occurs. You really don't need electric clothing if you make yourself like an onion in layers of all the clothing that you are already planning to take. Cover the whole lot with a roomy single-piece rainsuit to keep the wind out. I found that this worked great for me ,leaving Ontario on Feb .1 with temp at the freezing point and warming as I went south.Then as the weather gets milder you can peal off layers and stash them in your pack.
The heated handgrips on your KLR are a great idea, I have them too and they made the cold portion of the trip enjoyable. With this strategy you can wear your mesh jacket form the start, leave the black heat-sink at home.
As for the mountains of NW Mexico, do you really want to try them during Jan.-Feb ?- the coldest and snowiest ( yes it does snow in Chihuahua 's high country- this morning at 8am ET it wa already freezing -5C at Temosachic brrrrrrrr)) months of the year ? Can you arrange another vacation at a more agreeable motorcycling season for that region?It might be no more fun than riding in the Catskills or Adirondacks in winter.Motorcycles at heart are warm weather conveyances , I woud stick to climatic zones that are pleasant, there are lots and lots of good roads to explore in warm zones of Mexico and maybe tag on Guatemala and Belize while in the neighbourhood.

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http://advrider.com/index.php?thread....207964/page-5 then scroll down to post #93