Mr. Sixty - Everyone's right that smoking in FKKs is pervasive. Almost no way around that. As a lifetime non-smoker, I just decided to gird my loins and deal with it, same as with strip clubs in America. It's unfortunately part of the price to participate in what otherwise is an unbelievably awesome pastime.
Earlier in the day will, however, help with the second-hand smoke concentration, and I'm sure any of the girls would be happy to munch a couple tic tacs on the way to the zimmer that you could politely offer. Also, if visiting in good weather, you might find outdoors sex, or sex inside facilities like free standing cabanas or lodges with open windows, to your liking. FKKs such as Oase, Goldentime, Villa Vertigo, Mainhatten, and Sharks have beautiful lawns (some with pools) that include these facilities. Or, if you're okay with a little voyeurism from others, just revel with your favorite girl right out in the open in a hammock or on a large deck bed. I've seen that many times. Nature can be quite an aphrodisiac and your lungs will thank you.