I am currently a full-time male stripper and go-go dancer in the Chicago area for both straight and gay crowds. I've been dancing for over 12 years now. The truth is that some male dancers "fluff" (e.g., masturbate until their penis is about half to three-quarters hard) and then "tie off", which just means put a cockring around your dick to trap the blood in there. It'll keep it semi-hard for about 15-20 minutes... after that, it starts to become a little uncomfortable. Some guys will be in some corner of the dressing room, watching porn on their phone and trying to get the blood going. I've never had any success doing that, as I need a little more privacy and a little less testosterone around. What I do, personally, is haul my penis pump along with me and put it in my bag. Before I get on stage or the go-go box I will get my dick hard with the pump, put a cockring on, then get it hard again with the pump... When I take the pump off the second time, it's about 3/4 erect... perfect for fitting into a thong or briefs.
I've not run into one single dancer in this city who uses a sock or any other sort of prosthetic enhancement. Customers WILL come up and honk your junk as they tip you (both male and female), and if you're wearing some fake shit, they WILL know... then the whole club will know.
As for being nude vs. in underwear, it really depends on the place and/or venue. The law in Chicago states that any dancers have to wear underwear that cover both the front and back when dancing at a public venue. The law is rarely enforced, however, and some clubs will let you wear a thong or a jock strap if you prefer. The only time you can really get fully nude is if you're dancing at a private show, such as an afterhours party or a bachelorette party at a hotel or house.
BTW, we seldom make 500-700 easily. The usual Friday or Saturday night gig will net you around 200-300... Seldom less, but sometimes more. The only times you can really expect to make 500-700 in a night is if you line up more than one show, get lucky and have a high paying customer take an interest in you, or during busy party weekends of the year (Halloween weekend, New Years, St. Patrick's Day, etc.). It's definitely not the "norm". As for flat-out prostituting, I'm sure some of the gay or bi dancers do that, but I never have.