That question is similar to how many people can you fit in a Volkswagen Beetle. No more than you have life jackets, no more than you can evacuate into the water in one minute, no more than can get along for the duration of the ride, etc. Figure you can handle as many as there are seats but at some point don't expect to get on plane without redistribution of bodies.
We figure we have had as many as 15 on board and use the same calculation as with our camper, seats X number, sleeps two.
CG, will probably be interested in adequate, appropriate safety equipment etc. Call them and ask for recs and info, they're on your payroll and should have an interest in prevention of future work invloving your rescue. The States might be of some value but my experience in IL & MO puts this in iffy territory.
During one of the floods several years ago 8 of us had gone to our harbor on the MO side of the MS river and had various plans to return to the IL side where we had cars, boats, and rides. One of the folks was returning in a 27 cabin boat with a single 350 OD. He offered a ride to us and we took him up. These were big people, almost all over 6 ft and probably averaged 220+ with 2 of us in the V, 2 in the cabin, one on the cabin steps, it finally came on plane.
There are no standards for capacities for boats above a certain length. There are many calculators available online. And while I don't like POP Yachts. This was just a simple google search I did with some basic information into the subject. https://www.popyachts.com/what-is-your-boats-passenger-capacity-blo...
I've had 8 people on my 27' with more than enough power and room to spare. And the other day we had 6 adults, 1 child and 2 dogs on my buddies 22' cruiser. Had to move 1 person up into the v-birth to get the bow down on plane, but boat handles fine.