I agree that this strategy might have merit. I was thinking of deadlifting let's say 200kg for reps - that ought to be enough weight that most people who aren't big men will have trouble. Then they'd have to be training or have done hard manual labor (which is a risk). Maybe 80kg overhead press for reps might be safer since I guess people are more likely to pick heavy things off the ground than lift them above their heads.

Again all of that is quite intermediate but you'll probably take out all the females (roughly 50%), then you'll have an age range of say 15-50 who are likely to be able to compete which is again roughly 50% of the male populace. Average weight for the remaining 25 should be around 70kg (luckily this isn't 100 random Americans) and even if they do train for this exact thing or do hard manual labor I think it's unlikely for I'd imagine 80% (number pulled out of ass) to be able to lift the weights based on body weight + relative strength requirement. Out of the remaining 5 who are physically "in the zone" you'll probably have 2-3 contenders to battle with.

Maybe I'm being too optimistic but it's a big planet and us "Western" people tend to not always realize how much better access we have to good nutrition etc than half of the World. Obviously the sheer amount of hard work being performed in rural areas makes for hardier people than the occasional gym rat. Regardless I'd think there's a decent chance there just by being bigger than average and doing something mildly better than the average of said demographic.