@Aboutown, I may have already shared my tips with you via DM, but so that the next PL sees them when he find this thread:
It is $110 every hour and comes with a bucket of beer/drinks. You can alternatively pay an exit fee of $330 and they won't bother you all night.
This is the gist of it. However,
* Up until about a year ago, as @putatester experienced, Cas and Rizo would charge a whopping $300 bar fine to have an Off the Clock chica in your room. This is no longer the case. In the past year I have brought OTC chicas to my room at Rizo several times without any fines. Wingman @Zbott has done the same at Cas. So this is the biggest workaround. When I meet a chica I like at HK, I always ask ¿A qué hora terminarás de trabajo esta noche? / What time do you finish work tonight?, so that I can strategize on whether I might convince her to meet me after she clocks out. YMMV with this approach, chicas work an 8 hour shift and most just want to go home when done.
* You won't pay a bar fine for a street girl or a girl from another club. I had a chica from D&G in my room for a long time recently, no fines required. BT is one exception, since it's owned by HK, it's the same as having a HK chica in terms of bar fines. Chicago is another exception - girls there are straight up prohibited from going to Rizo or Cas.
* I've also had lucky tipping/bribing the hotel manager while buying a single bucket to get the time extended without paying the full price for 3 hours.
* I've also been able to sneak past the hotel manager when he's sleeping - no bar fine at all! YMMV. Like @Jascoi says, they are consistently inconsistent.
¡Alugna vez, tienes que alimentar el dragón! / Sometimes you have to feed the dragon!