litratista ...ladder is a good idea!
56 people is awfully wide. I'd suggest 3-4 rows, but shoot a little wide for cropping.
Shooting in daylight...watch for dappled shadows on faces...very distracting and not very flattering. Same with squinting.
Make sure you can see all the faces. If they can't see you, the lens can't see them. Take your time arranging them.
Shoot many frames!!! You may need to composite a face or two in the end...someone always has their eyes closed, but not in every frame...better 3 individual pops than 1 burst. Also, vary your exposure just in case.
Be aware of awkward foreground or background elements...telephone pole wires running thru heads are really distracting as is anything immediately in front like a cluttered table.
I'd also suggest taking subgroups...like all the aunts/uncles...all the kids...individual family groups etc.
Good luck, Paul