Kyle, most of us 'old' people don't try to shoot the whole 20 hours. We'll go out in the daytime, come back for the dinner, goof off playing some games (like last year's cornhole) and then when it gets dark we head back out on the water, shoot for several hours then come back and take a nap before weigh in. Since it's a 'big 12' it's not as important to be out there the whole time.
This year we're moving dinner later. Instead of being ready at 5pm, it will be more like 6:30pm. (bowfishing between 6:30pm and dark usually isn't that great anyhow... so might as well eat.)