The hardest climbing I ever did was riding from Placerville, CA to Kirkwood, CA in one day. The DeLorme software calculated the total climbing that day at 11,000 feet. There were long stretches where I could walk or ride the bike at the same 2.3 MPH speed.
Last year in France, I had to climb over two 1000 meter cols on the same day in the rain. I was beyond tired when I got to my destination that day but I was able to do it.
I clearly recall thinking on both of these days "Now, what is it about these experiences that I find so enjoyable?"
Unless the climbs are particularly long and steep and/or your bike's gears are not designed for loaded touring, you should be able to handle most any uphill by grinding away at it until you get to the top. If you get tired, take breaks and keep eating. The real problem comes with inappropriate time schedules, that is, trying to get somewhere without setting aside enough time given the terrain.
Clearly, the best way to know what you can do is to load up the bike and do some of the hills that are outside of town!
Ray