For my trip last summer from CA to AK I went with the K60s F/R. No regrets, very good in gravel, OK in mud and decent on pavement.
Like you I didn't want to change tires during the trip. I have 8000 miles on the K60s and they will go another 3-4K.
I'll probably go back to Tourances as my normal riding leans more to street with a little gravel.
'02 R1150GS ADV "The Tank"
"I fire up the willing engine,responding with a roar.
Tires spitting gravel, I commit my weekly crime."
"Red Barchetta" By RUSH