If the move is a once-off, build a timber cradle. The whole container movement is quite complicated and hopefully your local association will help with loading!
 
One modification to the loading process would be to: skate the boat in; jackup and remove.
 
Remember that the boat needs to be tied down in the container or provide bracing to stop the boat moving in a pitching sea as it will cause damage if the boat rubs inside the container.