I have seen a number of hops trellises shorter than that with decent yields. They can be grown on 6-8 foot trellises if you are willing to spend the extra time require to train them to a horizontal. It is just easier to grow them on a 20ft trellises where they will just climb straight up a string.
I use welded wire fence panels for trellises. The top of the panel is about 7 feet above grade. I train them horizontally when the bines reach the top. I may not get the maximum yield, but I get more hops than I can use in a year. 10 feet should be fine.