Well, first of all, if I had a 550 cow tag I would focus on that. Way better chance to tag than finding a bull.
There probably are places where your chance to kill a bull late does not plummet as much as that particular unit. With the rifle pressure in there, any bull that sticks his nose out of the reprod is likely smoked. Smart ones are in the reprod (and there's getting to be a overabundance of that). Basically hunt what might be safe zones. Miles of reprod is tough. Out of the way, huntable timber is good. Any places that can't be seen from any road. That's where you'll find most cows too btw.