One problem with hills is the slower you go, the more time you spend on the hill
I only did one tour so far, 2,000 miles in 30 days of riding, TX - NY....
But this is what I discovered.
There is absolutely no reason to suffer on these things, if you're straining and getting tired you're doing it wrong.
Rt 303 in Cuyahoga National Park OH were the first hills that whupped me, the previous 1,300 miles or so from San Antonio having been no problem, 17 gear inches comfortably had it covered despite the 40lbs of gear I was packing.
To put things in context, if I walked a total of half a mile out of that 2,000 that was a lot, but there were more occasions where I wasn't having a whole lot of fun. And on a 70 mile plus day, mashing ain't fun.
Having the option of spinning along at 3-4mph wouldn't trouble me a bit, those hills I could effortlessly spin up on my 22-tooth granny were enjoyable. I would study the flowers as I crawled past, listen to the bird songs, even looked at the bugs I passed crawling on the pavement (two degrees in Entomology here Yo 
).
Mike