I'd rather just kill mobs when it's dark outside in that case.
You don't have to make it fully manual.
Dig out a plus shape and put water on all 4 edges, then dig out the middle 2x2 area 23 blocks down. Finally, make a stairway down below so you can punch the mobs to easily get their drops AND experience.
EDIT: You'll need to make the water flow out 8 blocks so it stops right at the hole, so you might need to dig a little farther back, too.