I live in Austin and ive done almost that exact route before.. we started in Brownsville (the bottom),, came up through Austin and continued on north to Alaska. we took a ferry around Canada however.
you can see our route and follow the blog to get an idea what conditions were like here.. www.trackmytour.com/310 our route will take you all the way to Bellingham WA and you could basically head north from there to Vancouver.. i highly recommend crossing the Rockies in Washington where we did. the cascades mountians are absolutely unbelievable.. keep in mind that our route was slightly engineered around
passing through towns where we have friends or family or sometimes a warmshowers.com connection. two months is more than enough time to get ready. i had already done a few long tours before this one but the two riders that went with me had previously only been riding there bikes around town to go to bars or get breakfast tacos.. etc.. obviously,, the more you train beforehand the better you will preform on tour,, but to be honest,, if you just pace yourself in the begining and gear correctly you will all be in great shape by week two.. id be happy to answer any other questions for you guys.
feel free to email me personally if you want. zhall1000@gmail.com

-Zach