The mod is unfortunately not very vampire friendly.
The "opening hours" are outside the times when a vampire can move halfway without being burned by the sun. (Not every player uses sun residency. I lost my master vampire because of this mod!)
1.) Realistically, many shops especially in Europe where I live are open until 20 or 21 o'clock. America around the clock? 6:00 p.m. is just too early to close. Better opening hours are 9 am to 9 pm. ("better" for vampires in this case) Besides I don't know any hairdresser who is open at 6am :)
2.) When a vampire goes to the hairdresser, the character only becomes invisible, but he still stands at the "spawn point" while the sun kills him. The mod should give the character an invisible sun resistance buff before he "disappears" and remove the buff when he is done with the hairdresser. That would solve the problem I guess.
3.) Keep in mind that vampires have a negative buff that you can choose to give them that makes them very vulnerable to sunlight. So that these players (like me ^^) can also benefit from the mod and don't lose their characters all the time, you should think about changing something.
Edit: Oh almost forgot: it would be great if you could turn off the hair growth for a special sim. My aliens are all eggheads that shouldn't have hair growth (I think that makes the races more interesting when each has something that the other doesn't have. If everyone runs around with a bush on his head there is no more variance in the game)