Man, great write up! I feel like you guys 15 years ago when I was figuring it all out. I still am a bit perplexed as to the one response bulls and how to handle that. My only suggestion is that when you hear a bugle, you gotta get close before you respond,which if sounds like you tried. I would try to get in close and respond with a cow call. If the bull responds at that point, challenge him.
Despite one set of advice, you can too chase them down. If they're bugling, you keep chasing them. I killed my first branch bull this year by doing just that. Kept after him and finally got to where he was gonna bed. Got in close and cut him off and challenged him while taking a tree. That was enough, he came and I shot him.
Keep moving too. Don't bugle and call repeatedly from one spot, keep moving and break stuff, be noisy, sound like an elk. Shooter needs to be mobile. I don't like being on my knees, if I need to take a side step or make an adjustment then standing let's me do that. Unless I'm in the open, then I'll kneel.
Good luck on your return trip. Great, honest write up!