Modern Lightnings have a better flotation setup than the ones we used to sail (which had none.) We got a gentle tow after capsizing in order to get the water out over the back of the cockpit. I crewed at the North American Championships one year, (100 boats), and as Caleb suggests, it blew about 25 knots. Coming from Long Island Sound, we had never planed in the boat before. We were all High School students, and weren't as heavy as many of the older sailors. To keep the boat flat we loosened the hiking straps until we ended up sitting on the topsides. (This is now called "droop hiking".) With that much wind, and a long fetch, the waves on Lake Ontario built up into a quick chop about two or three feet high, which the boat handled without too much trouble, though it was pretty wet. Before going out in conditions like that it might be better to get some practice in lighter air.
Mine is a 1977 Holman Nichols#13121. It does have the big molded in seat/ flotation tanks. I will have the boys tip her over and practice righting her in the first few times out. Thanks