I tend to monitor on the louder side of things (mid to upper 80's) while making processing decisions, and then give my ears a break from this during captures and interspersed periods of monitoring lower than the usual as well. But got to say hip-hop is not made to be played at a "calibrated" level - it's made to be seriously cranked up - and the producer or artist wanting to be able to hear it at above an 83dB spl level for at least some point in an attended session makes perfect sense to me.
I'd say one requirement for any "mastering grade" monitoring system dealing with more aggressive and club oriented genres is that it should be capable of handling "club play" levels without any break up and without any threat of blowing a driver. If you need to prevent your perspective from being thrown or from getting instant ear fatigue then I agree you should just leave the room during the time your clients are listening at the higher levels, and I'd say that truly dangerous to the ear levels should not be allowed to be played to the clients either. But to me if you're dealing with producers who truly want to hear how things will sound at levels that are likely to be used in both club play and by a good percentage of their targeted end listeners, then it's worthwhile to make at least a small effort to accommodate them.
(I love working on hip-hop btw.)
Best regards,
Steve Berson