For someone who wants to hike & shoot: don't ignore the Western U.S. & Canada! There are certainly some good photography itins up in the far northeast U.S. and eastern Canada, but the west is definitely worth a couple weeks of your time.

I know you don't want to do this whole trip in the one-direction manner required by the major alliance RTW tickets, but it still might be worth looking into whether it makes sense to overlay an RTW ticket with some of your other travels.

How frequently do you intend to return to base during the trip? A Star Alliance carrier with generous stopover rules on regular awards might help you get back to FRA every now and then...