How much sous vide is possible?

There isn't a lot of published information about the density of meat but for ease of calculation lets assume its 1.2 g/ml. That would put the volume of 24kg of meat at 20 litres, almost half of the sous vide, which would generally be considered too much meat and not enough water bath volume.

I think i've seen somewhere that 3:1 water to meat is considered the maximum, but I can't remember where this came from.

The main issues are the kw rating of the heater, the homogeneity of the water, ie no cold spots, ability to raise the temp of the meat quickly enough that it doesn't stay in the danger zone too long.

One advantage of sous vide is cooking to temp and quick cooling, so you might think about pre-cooking and chilling then re-heating as an alternative approach to cook to order.

By this time you'll already have discovered whether you can succeed at the 25-30 Kg level. That's about 66 lbs. you're hoping to fit into a 53 quart water bath. It's going to take a powerful cooker to bring that much up to temperature at once. I've cooked 5 lb roasts in my 7 quart cooker with ease, though, so my guess is that it will be possible. Perhaps you'd better keep a couple of big water pots boiling when the meat goes in--you can use it to help bring the water bath temperature back up after the meat goes in.

To my way of thinking, the meat will physically fit in the vessel, and with enough circulation the meat should cook OK, but the biggest issue you're going to have will be 'variety'. With that much meat at once you'll be able to feed perhaps 100 people, maybe more. But 100 people won't be able to agree on a single unified choice of meat. Some will enjoy beef, some pork, some chicken, some fish. I've known people who endured allergies that prevented them from eating any meat that was not lamb. With a range of meats comes a need for a range of cooking temperatures. Dark meat chicken calls for temperatures in the range of 156F/69C, light meat chicken favors 140F/60C, pork tenderloin 138F/59C, medium rare beef 131F/55C, and some fish will do well with about 35 minutes at 122F/50C. To prepare a variety of dishes will require several vessels at several different temperatures.