Take a tarp and some bungee cords or straps to secure it, same as you should do for a green lumber run (I didn't and am paying the price for hauling wet lumber 65 miles at interstate speeds). KD or not, it will still benefit from a bit of acclimation time in the shop before milling. As long as it doesn't get too wet, you shouldn't have any problems. If it does get real wet, sticker and strap it when you get home.
The tarp will also protect it from road dirt that can affect the life of your cutting blades.
If it just gets wet loading it, the moisture will be on the surface, and should evaporate without any serious undue consequences as long as it is stickered and strapped after you get it under shelter.
JMTCW
Go
Please wait for Scott or Jeff to reply before taking my word for it. They know much more than I do.