Sleep is the last part for most people to even out. Unfortunately that can run longer than you would want to take Xanax nightly for. People sometimes even report waking up a lot in the night even a couple of months after kicking.
My recommendation would be to start experimenting with some non-addictive sleep aids, such as (OTCs) doxylamine succinate, diphenhydrinate, dimenhydrinate or a non-addictive prescription sleep aid if you have a doctor you can go to. I just recommended Remeron (Mirtazapine) in another thread, which is actually a mild anti-depressant. I used to use it often when sick or recently kicking and it helped out a lot. Very strong, leading feeling of natural sleepiness. Plus if its mild anti-depressant effects prop your already positive-seeming mood up a bit as you venture forth into sobriety, that could only be a plus. It is not an abuse-able drug so most doctors are fine if you start the conversation with them about it.
One thing you can be pretty comfident about is that once the WDs are over, you will get SOME sleep each night even with no aids. Three to five hours is about the norm for the first few weeks, and this can work in the short term. I do hear you that a good night's sleep really makes a world of difference but I think you are clear of needing to worry about going days without sleep even with no sleep aids.