It is more difficult on the West Coast as well. Even years ago, it seemed to me that it was harder to get in on the East Coast, but that could be because I was an out-of-towner, and just like on the West Coast, bookers don't see an ongoing financial return on the horizon by taking the time to vet a visiting customer that may be one and done.
What I have done to get into most of the East Coast agencies is to get a vouch from a touring Kgirl that knows me. When I see touring girls in SoCal, it has always been my practice to exchange phone numbers with them (unless I think they are BSC) for the reason that I, too, travel a lot, and if I'm in another city they happen to be working in at the same time, I could see them at the other places where they tour. So when I'm on the road, and see a girl that I know is also in town, and who I have phone number for, but she is at an agency where I was not yet approved, I would text HER first, and tell her that I'm in town and wanted to see her, but that I'm not approved with her booker, so could she give the booker my phone number and tell him/her that she knows me from SoCal and its alright to give me the appointment. Then when I text, I'm already approved the same as if I was an existing customer. Once I see the girl I know, I am in that bookers phonebook, and can see any other girl I want who's working there going forward.
I have used this method to get approved at over 15 agencies outside of SoCal, and it ALWAYS works. Having a girl that is working there vouch for you is the best and fastest way to get in. The booker doesn't have to check other refs or do any vetting at all. After I got several of these, then I could also use these bookers on the East Coast as additional refs at other agencies, just like I had always done in SoCal.