I live in central New Jersey and our frosts run the same as yours, from the end of September to mid-May. We also get temps in the 80's and 90's, and very high humidity. I find that summering the plants outdoors, even for such a short time, does wonders for them. Three or four hours of sun is okay, but what part of the day? Morning sun is good for all plants. The afternoon sun is good for light loving cattleyas, laelias, dendrobiums, etc. Late afternoon sun is good for oncidiums, encyclias, miltonias, etc. The phals and paphs would have to be protected by an umbrella or shade cloth of some sort.