CliffordK

At least around here, any hill that hits 33% only does so for a couple of blocks at most. As you say, your hill is average at 13%.

Sometimes I even wonder if the "max gradient" is so short that it is difficult for an accurate measurement by normal GPS and mapping. A car length or two?

Still, we have some wicked hill climb rides up in Portland, some of which I struggle with.

RondePDX

It doesn't look too bad from the maps, but at every corner, one turns the corner and back up a hill at 10% to 20%, or more.

As @Tacoenthusiast suggests, just go and try out your bike like you have it. None of us can tell what it will be like for you do do the climbing. You may have to stand up from time to time. Having pedal retention (toe clips, clipless, etc) will help with short-term power to pull over some of the steep stretches, but can be a pain with starting when stopped on a hill.

One thing about the super low gearing, at least for me, it just means I go slower, and ultimately spend more time on the slopes.

As far as the rides above... I'm no beast by any sense of the word. But, the first time I attempted the rides, I had 39/23 (1.7:1) low end gearing. That really beat me up. I changed to 34/23 (1.48:1) and it was still hard, but mostly doable. I've also done them with 41/26 (1.58:1) gearing. Not fast, a few stops, but I power through the rides. Personally I don't intend to hit 1:1 gearing until I hit age 70 (or I am carrying/pulling a bunch of extra weight).