Well to avoid the opiate WD. Your gonna have to be on sub for a little bit. You can take sub for a week and stop after that but you will probably feel some WD. Get with your dr at rehab, but whatever they say start tapering ASAP!
What about a 5-7 day rehab do you thi j that's long enough to avoid withdrawals and be ok without the subs?
I would not stay on it for a long period. Maybe start at a high dose like you said but try to start tapering right away. If you do a 28 day rehab try to be off or close to off of it when your getting out of rehab