I think the tight main downwind is right, (much tighter than I'd ever do on a keelboat) but not so that it's stalled.

The 28R seems to be a pretty forgiving boat - the worst stuff we've done was fixed by a major ease of the chute. Not a foot or two, more like 7 or 8 feet. Have your chute trimmer hold about 5 or 6 feet of slack between the trimming hand and the "lazy" hand. If the bow stuffs, then blow the chute to get the boat back on it's feet. Also I'd plan on driving a little deeper than normal in really heavy stuff to both max VMG and lessen the influence of the main wrt pushing the bows down. Finally - crew weight as far back as you can...both helm and stern.

If you ease the main when your bow stuffs (assuming it's tight to begin with), you're just going to power it up and push your bow further down until it's truly to the point of dumping air. I don't know about you, but our mainsheet tends to get fouled up when we try to let it run quickly.

It's edgy stuff, but I can't remember the last time I heard about someone flipping a 28R in wind/leeward conditions (hope I didn't just jinx us all).