I agree, 39 stone breaking strain seems plenty. The problem is the knots, wear, UV damage and the angle at which the hammocks hung from.
Knots can derate the line by 60%, that brings the paracord down to 200lb odd. Take off some wear and UV damage to boot and it can be much lower. All it needs is a small stone to work inside the kernmantle, a small unseen nick, a heavy sit down in the hammock and 'Twang, thump'
The commonly accepted formula for working out the required BS for ropes and cords is 4-5 times the maximum working load, not accounting for knots. Paracord has a factor of just 1-2 in your setup as its hung.
At 30 degrees, the force exerted on each end of the suspension is equal to bodyweight. At 10 degrees, its 5 times bodyweight.
Somebody reading your advice, could well tie their hammock up for the first time too tight, sit in it and really hurt themselves. There is a good reason reputable hammock makers don't sell thier hammocks with single paracord suspension-they'd get sued and righlty so.