Many, if not most, established poker rooms (with big games) have safe deposit boxes. However, acquiring one is often not quite so easy.
At the Hard Rock, Hollywood, you must be an "established player" at $5-10 NL or bigger. Than, IF a box is available, the shift manager has to sign off for you to get it. As a low roller, I've tried periodically to no avail, and I have an established, good relationship with the shift managers and director of operations. But that just does not help me get a box. damn it.
At other poker rooms I've visited, if boxes are not available, the casino will be happy to establish a "players account" where you can deposit or withdraw your cash. Unfortunately, that does leave a paper trail.
I can offer no insight on getting one. Just keep asking.
I did try the $20 trick at the Hard Rock for a box. That did not work. Than again, I did not expect it too. My bank only charges $30 yearly. lol
So I remain a "low roller" simply because I do not want to carry more than a couple hundred when I commute to play poker at HR. And every time a game breaks out that I would play, I ask them to pay my ATM fees so I can buy in, mentioning that I can not get a box. They won't pay the fees so I won't play, and that's that. I do not want to buy in short stacked.
BTW: I only play limit games, but would play much bigger that they usually have. IF I could keep my money in a box.