wrench source?

Any you guyz found a source for a 5/16 open end wrench with
a really REALLY long handle? Just went thru the annual
rear drum brake adjustment and found it less comfortable
than usual (old age? Rhumatism??). I would like a wrench
long enough to work the adjuster from below the leaf spring.

I can find long handled wrenches in larger sizes, but so
far nothing in 5/16.

(stupid, I know, but we all need a quest)

chuckC