keep the companionway hatchboard in and the slider closed and sail until either you or the boat cant stand it anymore.....
if waves splash in, it will drain out of the cockpit thru the rear scupper/bailer hole....
this is providing that the hose on the bailer hole is not rotten and letting the water dump into the hull, or plugged up so that it doesnt drain at all.....
but if you start taking on water into the hull, then you are going to have serious problems real soon....
we cant sure what kind of condition your boat and rigging is in, or what you carry for safety equipment..... or how physically able you are to handle the conditions you are speaking of, but if you can keep the water out of the inside of the boat, it will float forever, but a breakdown of boat, equipment, or personnel may allow things to happen that would be better if they didnt....
and in the original plan, the macgregor boats all had foam flotation in all the inner compartments to create positive buoyancy in the event of the hull filling with water. this is a safety feature that I wouldnt want to test, but according to the manufacture, it will keep the hull afloat enough for you to have something to hang onto while your waiting..... some people have removed the foam from their boat to create more storage space, so check yours to see if the foam is still in place. happy sailing..........