I love that sort of conditions. Upwind the J/30 is rather fun to drive (as long as you've got a bunch of bodies on the rail keeping the spray off you).
Like Bob, we set the rig up pretty tight. Uppers are 45 on a Loose Gauge B, lowers 44. We don't change the forestay, but that probably would help a bit too (moving the CE of the sailplan forward and reducing weather helm).
With backstay, outhaul, and mainsheet on hard, the main looks REALLY flat.
On Lake Michigan with the wind out of the NE, we get some pretty good waves... perhaps what you'd find on Buzzards Bay. I drive around the waves a lot... the main trimmer has to play the traveler constantly... dropping it as I head down the back of a wave to keep from heeling too much.
If we're still overpowered, we'll ease the mainsheet so like Bob we'll only be using the leech of the main. If we're still overpowered, we'd use a flattening reef (if you happen to have one of those anymore).
In a westerly offshore breeze, Loch Mich is pretty flat in Chicago. In those conditions, we point really high, and drive mostly by heel angle, feathering when a gust comes along and we start to heel. Probably nothing faster for it's rating than a J/30 with enough weight on the rail to hold it down.
