Well, on the US LCAC, as you can see in this 1st picture, there is a compartment that troops can ride in on the right side forward, with two doors.
This compartment takes up the entire area on that side where you see the LCAC-59 marked in this second photo. As you can see, on the other side, there is a smaller area that can carry more troops behind the pilot house.
If they want to carry a lot of troops in compartments, they do not need to wait for the Ship to Shore Connector. They already have compartments for troops that can be stored (and taken down) right in the main vehicle area.
There are nicer ones (for humanitarian duties) like those filling up the entire area of this Japanese LCAC:
Finally, the US Navy LHDs and LPDs can also carry another landing craft, which also carriers vehicles and/or troops. They can carry a lot of troops at once and are designed to fit right into the well deck: