One of my biggest pet peeves is when a flight is lightly booked (where noone should be occupying middle seats unless they're with a group) and a person insists on sitting in the middle of my carefully chosen row just before the exit row. Apparently that's often when people just 'give up' and sit down, despite passing up several middles before me and seeing many, many open aisles and windows behind me.
I'm always at a loss when this happens, and usually end up moving a few rows back, explaining pointedly that there is no need for strangers to sit three wide on a lightly booked flight. I try to be nice about it, but I'm sure my irritation is sometimes evident.
Anyway, for the OP, I honestly think A-61 (A-List) boarding gives you the best of all worlds if you weren't expecting to get exit row anyhow. You're the one that gets to choose your seat mates, instead of the other way around. If I flew alone more frequently that would be my semi-permanent plan - it also works particularly well for someone who likes to stay in a lounge right up until boarding.
PAX62 perfectly describes how we handle it when we fly together - I aim for the aisle right behind the exit row, my largish SO comes a bit later and I switch to the window. We have a reasonable level of success getting the row to ourselves. That said, I ask the FA how many they're expecting, and proactively offer the window to smaller people on sold out flights.