For your tour I wouldn't bring rain pants. With the temperatures you'll be seeing, whether to bring rain pants basically depends on whether you want to be soaked by rain or sweat. I'd choose rain.

If you are still looking for a pair, I can say that I've been very dissapointed with my Frogg Toggs Road Toad rain suit. The jacket works well but I get soak through in the crotch of the rain pants. I think it's a combination of the seam tape having torn from the cycling motion, and the material not being fully waterproof when it is compressed and abraided between you and the bike saddle.