I'm not sure what distance you're talking about over the lake but I agree that reading wind over the water will be difficult. At over 1000m (1093 yards) I look at wind from the the mid point to the target rolling through the parallax to see it and sometimes make up to three wind calls then average them with slightly more emphasis on the final third distance as the projectile is slowing by then. I've very often seen wind going in completely different directions in these cases so have found it valuable to bracket the target (point of aim) also. It's worked for me. At 1000m and beyond it becomes even more critical. Wind and gravity...serious factors as you know.

Working on breathing and trigger-pull is a constant thing, I do a lot of dry firing which helps, and costs nothing. I also do it in a more kinetic way. Run, rifle in hands, to the shooting position, drop, assume the position, acquire the target and go through the process of dry-firing on it...The accelerated heart rate shows weaknesses. I use cluse up slow-motion video to record the process at times also, it highlights issues although I've not had to do hat for a while, only if I think there's something wrong. That breathing-trigger-pull process is so critical so I train around making it smooth under simulated situations which gives me an overall better result when things go live.

300 Win Mag huh? I like getting behind that calibre...rarely enjoy lugging the rifles around though. Lol.