Elkshed, you do realize that when you are using a howler to locate, coyotes could very well be coming to you at about the time you're driving off, don't you? Why not instead, wait until first light, set-up to call in a likely spot, start with your howler, and go ahead and stay put just like any other set. Do some distress calls, etc., and if by chance, you here coyotes howl in response, but none show, then move toward the vocal response you got.
By driving around and howling, then driving off, you're basically using a good calling tactic, but not utilizing the results that could come from it! And why beleive that the coyotes that responded will still be there when you get back to them?
For what it's worth!