Doing it outdoors / public sex
If a girl is a good performer, she has nothing to lose doing public sex. It's simply good marketing of her skills and would probably increase her revenues. It's the scammers that most often will refuse. Sometimes public sex can make a mediocre perfomer improve her performance as it otherwise would be bad marketing.
Not every girl will be doing public sex. As with everything else that is a little bit different than the standards you need to shop around a little. But it's not really difficult to find someone at the FKKs (speaking basically from an Oase / World perspective). But sometimes you need to find the most discreet place to make her comfortable. Or; if it's your first time, you can simply ask the girl to find a discreet place for you. True exhibitionists is a minority, but they do exist (Swiss Michelle at Oase was legendary, but there are others).
The most common reason for refusing sex in the outdoors is bad weather. It's understandable. A girl's revenues is so dependant on her good health and she will not risk it if for instance it's too chilly. It's just not worth it.
Gents whining about "too little public action nowadays" should simply just do it first. Whenever I do public sex as the first (in the kino or in the outdoors), there is usually one or two other couples following in the neigbouring couches or sun lounges / beds shortly thereafter. Don't be shy. There are always other gents in the club having the same idea about enjoying free sex in the open. Communication between the couples, if any, is usually just cheerful laughs, "viel spass!" or thumbs up while enjoying the act. Very relaxed.
Not sure if Asian gents are more shy by nature or by cultural barriers or at all, but one of the happiest gents I have ever seen in a FKK (by the look of his smile and excitement) was an Asian dude walking back to the money lockers with his girl after having had his first public session ever in the garden. "It was my first time!" he repeatedly announced. So just go for it if intrigued by doing it in the open.
Yes, let loose. Be free!