with a 20 g.i. low it will be fine, I biked a good chunk of the Pyrenees and west coast of the States on my old touring bike that I changed stuff to get to 21 g.i. , and from Montreal to Boston on that cross bike of mine with a different cassette so about 22 ish , and on these trips, never had to walk.
The times I've had to walk (which I don't like doing, bang shins) it was eons ago on bikes with too high gearing, which made me figure out gearing and how to lower it.
Keeping the load down and if you do have light weight stuff, it'll be fine.
if you can, it's really good to put the hours in on a loaded bike, but if you're in relatively good shape and you don't load up everything and the kitchen sink, this gearing range works.
As another light person, 135, I can attest that we do notice more or less weight of a touring load, but you'll figure that out on your own.
to put gearing in perspective, the super low gearing on my Troll was because I knew I'd be carrying more crap, spare this, more tools, extra water, and I knew I'd encounter stupid steep stuff, 20% or more for short bits. In Latin America, the terrain and budgets and all that mean that you get way steeper stuff than we do in Canada or the US, and pedalling a heavy touring bike is easier than pushing it.
apparently the Appalachians are kick ass hard, folks here who have ridden them say they are harder than the Rockies.
hope you get out touring one day.. After a week on the road, you get the packing order, eating drinking, amount of sleep, etc in order, and it's cool when you start to feel touring fit too.
cheers
I appreciate all your insight and support so far! I am actually planning to go cross-country this summer.
Once I get the bike sorted, I'll post pictures and do some practice runs. In the meanwhile, and more so when it gets a tad warmer, I'll be doing daytrips and overnights outside my usual routes.