Ummm, Long trip, climate changes, comfort...UMMMM
Also consider somthing you could use on both bikes?
I got a pair of Joe Rocket Pheonix mesh pants from newenough last year for my trip, I then wore a pair of underarmor heat gear longjohns underneath. Then if I got hot, I spray some water on my pants with a mister bottle, it was almost cold when I rode, not bad considering it was 91 degrees out.
Anyway, those are some of the items that really helped me out for the haul.
You'll enjoy your trip more and spend more time in the saddle, which may also enable you to take more side routes.
I outfitted my wee for long distance touring, did a 1700 miler one week last year. There are numerous little gadgets from aerostich that make a long trip more enjoyable.
I always try to look at it this way though, at least with my cabelas points on my visa.
Its easy to nichol and dime, but how often do you get to lay out a Ben franklin?
Get something big, you can always get those cheaper things later.
"Pain is weakness leaving the body"
"Nothings possible until its done!"
"If ya can't afford the fine, take the lead!"