Have the same problem. Got a similar sized hatch back. When we go away I pack a similar amount of gear.
As soon as my wife sees it she decides she wants to take a bike!
I think the best I have done is 2 boards and 3 sails masts booms etc all on one side of the roof. Two bikes on the other side of the roof.
Luggage spread all around the car. Child on one side, dog on the other. Everything seems to fits nicely except my harness! It always seems to be the one odd shape that doens't fit.
This load is soon to be topped with the impending purchase of two surfboards