The thick cover is daunting as it seems we will be very close prior to any shot opportunity. But I'm with Rover, its time to get in their path, just above and below and let them walk on in. Always minding the wind, which appears to be flowing towards their noses (isn't it always?) If the herd bull appears to be getting by, then we might try a few estrous cow calls--it is 9/16, after all, and the first cows should be ready and the herd bull is waaay over due for some loving. If the herd bull slips by, then I'm hoping one of the satellites is just hot enough to come to the same sound. All the boys want some action, we are in close, so I'm counting on hormones to close the deal. Like Rover, again, I'm not introducing another bull into the mix, yet. I have low success rates with that strategy this close in; mostly I bust the cows with that bugle and the herd bull follows.
If all of that fails, I'd try to follow the herd. If they are close to bedding, they'll slow down and the bull will not want to bed as fast as the cows. That leaves him pacing around, looking/sniffing for some action; maybe getting cows up from their beds. If that wasn't working or as it was working, I'd use a few estrous whines. If that wasn't working then he'd get a combination of estrous whines and pants, huffs, and glunking to project the image of a satellite having hooked or trying to hook a willing and ready cow.