You might seriousily consider a BOB trailer for your tour, and gear. We highly reccommend a Eureka brand tent, we have had a 4 man timberline for 28 years and it still looks like new.
As we looked at tents for bike camping recently the timberline won out hands down except we wanted a big enough tent we could stash our tandem and trailer in, so we had to get a huge Wal-mart tent, but it still only weighs 10#. I would seriousily look at a Eureak brand tent, and keep in mind you might be spending more time than you ever imagined in it if the weather gets bad.
Our old Eureka has been used to camp in the sand on Lake Huron, and as a playpen for our two children. One of our kids and her friend got floated (literally) in it, and soaked do to camping in a low spot. It is a great tent, and we wouldn't think twice about using it if we weren't so worried about the bike and trailer leaving us or getting wet.
For a good deal, try Campmor.com.
Have a great trip