Long legged riders: Riding horses with small barrels?

I hear ya! I'm 5'10. I ride stocky qh's and paints primarily who are all around 14h unless their rope horses but back when I had to ride the narrower horses (used to ride hunters, eq horses and jumpers) I would jack up my stirrups a few holes, and sink deep in that heel which automatically gave me a tighter leg (something you could try, definitely helped me). It feels odd since your not used to having that tighter leg, just keep with it, you'll adjust.