The pandering, solicitation and prostitution issues come in to play when you ask the performers the question, "Would have have had sex with the other person had you not been getting paid?" If the answer is no, the performers are prostituting, the casting folks are soliciting and the producers/distributors are pandering. If you get a zealous prosecutor, you might find yourself facing prison time even if your release says that the money is for the rights to sell the images, not the sex.
As I understand the laws in Nevada, aside from the two counties that prohibit prostitution all together, prostitution is legal but other laws prohibit street walkers. If my information is correct, licensed prostitutes can ply their trade anywhere as long as they aren't doing so out in open view of the public. With proper licensing, you shouldn't have a problem in most of the state.
*Of course I am not a lawyer and these are just my personal (non-professional) opinons on the information that I have at this time. As always, you should consult a qualified attorney with any and all questions regarding the legality, or lack thereof, of any project that you are questioning.