They won’t interact as far as your typical toxic drug interaction. So no issues there. That said, long term opioid use has been shown to lower serum testosterone levels. Low testosterone levels can affect pain control leading to hyperalgesia, mood impairment, fatigue, and depression. So it’s not a bad idea to increase his test levels.
I understand wanting to strengthen his back. I went through the same thing when I took shrapnel from an IED.
That said, seeing that he has an addictive personality, he’s likely gonna be someone that has major body dysmorphia issues and starts abusing PED’s with wreckless abandonment.
He really needs to focus on strengthening his back natural at first. Then move yo PED’s. If I were him, I’d focus more on BPC-157 & tb-500.