The backflush with the smartwater cap for 20 minutes thing is interesting because most people would've just given up and drank straight from the creek. My question is what made you decide to keep messing with it that long instead of just boiling water on your stove or dropping a tab in your bottle? I've had a squeeze die on me before and my first move was always just to switch to chemical treatment for the rest of the trip, way less work than fighting a clogged filter. Did you not bring any backup tabs or a stove, or was the water source too silty to trust? And after 20 minutes of backflushing, was the flow actually good enough for the rest of the trip or were you just barely getting by?

That 40 foot wall in Tulsa is a good test because sag shows up worst in the middle. Here is the thing about the cheap ones though: the beam itself is usually fine, it is the self leveling that gets you. A $80 rotary can be off by an eighth of an inch over 30 feet and still look level when you eyeball it, which adds up fast over a long run. My move is to check whatever laser I am using against a known height at both ends of the wall before I start laying, and if the two ends match the string line I trust it. Also the cheap ones hate cold mornings, the beam gets dim and you can barely see it across a parking lot at 7am.