Quick update. After some trial and error I have come up with an alternative which should work for those cases I need it. Essentially bring the cable in from the top (or bottom) and connect the correct wires to the nearest row of connectors. Then for the other row run the 2 left along the left side of the fitting and the 2 right along the right and then connect them in. This way I can put the plastic connector on to hold them in place. Clearly this doesn't help secure the cable itself but it seems secure once the cap is on.