Welcome to Horizons Unlimited Merrie!?
There's lots of off-road courses available, though not many oriented toward big bikes and loaded-for-travel bikes.
Ask your local dealer if they know of something.
Depending on your timing and route, we've organised a great deal with RawHyde Adventures. US$100 off for HU people!
http://www.rawhyde-offroad.com/
RawHyde is based in California, but will be doing a course just for us at the Copper Canyon Mexico Travellers Meeting in September. Two day course.
Jim will also be at our Colorado Meeting.
As for your planned itinerary - that's a lot of ground to cover in only 6 months. The number one mistake everyone - and I mean
everyone - makes, is grossly overestimating the distance you can cover in x time.
You CAN do it - but I strongly recommend cutting the distance down. Do just Mexico and Central America, or just South America.
As an example, the RECORD fastest time from Alaska to Ushuaia is 35 days, done by the couple that also hold the fastest around the world record - at 19 days. Think about the difference in time there, and you'll start to understand what I'm saying.
Your speed and distance travelled in a day will be far lower than you think. We spent 9 months in Mexico and Central America, and it was about right.
Spend a lot of time browsing the travellers stories on the site, and you'll get a good idea of what there is out there, and how long it takes to see them.
And do try to get to an HU Travellers Meeting - you'll learn a LOT! North Carolina is a short ride away - see you there!