I cannot imagine doing 11% grade. Is there such a thing on USA Interstate Highway System? Surely not.
I'm going to try to keep my speed at 45 tops and with full jake on. Just hope a truck behind me doesn't get all antsy. He can go around. After all I have to wait behind them going up.
When I was taking my CDL training, I was taught to establish in my mind a safe speed for the grade I am on. Then brake to ~5 mph below that speed, release the brakes and let the speed slowly creep up. When it reaches the safe speed again, apply brakes again and reduce. Doing this cyclically gives your brakes a chance to cool between applications.
This advice is valid whether or not you have a Jake. If you are using full Jake and are still gaining speed then use the brakes as described. If the grade is too steep for this approach downshift to a lower gear but you may still have to use your brake as a supplement. Coming through Lookout Pass on I-90 I was in 3rd following an 18 wheeler at ~45 mph; I only had to use the brakes twice in the entire descent.
As for going down hills and worrying about other drivers, here's an old trucker quote that I like to keep in mind: "I can go down a hill too slow many times, I can only go down it too fast once!"
As for grades of 11% or more, if you don't like them don't go to Canada. Going around the Gaspe Peninsula a couple of years ago we got used to 14% grades (up and down) for several kilometers of length. There's one grade on the Cabot Trail in NS that is ~22%. We did it in our Class C, but I don't think I want to try it in the Beaver.
Lastly, to clarify my approach on grades when the Jake is providing too much braking, I rarely actually have to accelerate, but you will find there is a throttle position at which the Jake's effect is stopped but there is still no significant fuel being provided. I often shift the Allison to 4th so when I ride this "sweet spot" the transmission doesn't hunt gears, but, rather, just stays in 4th with the Jake being turned on and off as I wish.