Congrats!!!! That thing is a MONSTER!!! Sounds like a story you'll remember for a lifetime.
I've hunted deer and elk in the Rockies as long as I can remember. Heck I was concieved on a deer hunt but let's not get off topic. I've always wondered how run and gun hunting/shooting in the high country compared to military shooting. It sounds like they can be two different animals in some cases. I spend a lot of time and energy practicing for scenarios exactly as you found yourself in. I've even passed up some shots because I couldn't get steady enough.
You probably have forgotten more about shooting than I know. With that being said I have always believed that proper breathing was important to accuracy but when I'm out of breath I have found that if you can aquire your target quickly it's helpful to hold your breath and you will actually be a bit steadier. Works for me anyway. I only hold my breath though when I'm panting heavily......it's not something I would do in a calmer situation. Has anyone else tried this?
When placing a trail camera don't just look for a well used trail. What you want to do is look for a freshly used trail off by itself that goes from a north facing ridge, thick forest, brushy knob or some other similar bedding area to a food source. Don't forget water sources. Especially in the summer months the deer need water so look for a good trail going down too a creek surrounded by thick cover and place the camera 100 yards up from the water source.
Scent control is very important...