Mom,
There are no cabin loops by the marina - only a pair of individual cabins in loop 100 for "VIP" use. A golf cart will get you to the boat dock as there is lots of cart parking down there particularly near Trails End.
The cabin loop nearest the external bus stop (The Outpost Depot) is 2800. Any cabin near the entrance to that loop is a 5 minute walk to Outpost (if you are in the far reaches of 2800 then double that. It's a big loop). If you want the shortest walk from 2800, ask for a cabin near the entrance of the loop (lowest numbers or highest numbers in the loop) when you check in.
Good luck!
Bama Ed