We use the Descanso Beach Ocean Sports service to move our gear and kayaks from the Freight Line to Lava Wall and back again. Been doing it for the 11 years we camped/kayaked in Catalina. That's their boat in the second picture.
JRUIZ is correct, the logistics part can be difficult as there are no roads to the 11 boat in camp sites. We do see folks kayaking to sites where they have their gear on their kayaks. Since you have to pack in water our 7 day stay makes that impossible for us.
Here is their website.
https://kayakcatalinaisland.com/kayak-camping/