My driveway ends with a 4' drop onto my side lawn. I was thinking of extending the driveway by one car length by building a pressure treated deck. I'd like it to be strong enough to hold a car but the only purpose is to park my motorcycle trailer on it. With both bikes in it the trailer it could weigh as much as 3k pounds. I believe a normal deck is built for a 40 psf live load. What would one strong enough for a car be?