I wouldn’t do this. Methadone has a long half life and will still be around after the patient leaves. You need a special license to prescribe it. Americans like to abuse drugs. If one of these patients decides to take a couple of extra oxycodone from their prescription and dies, how’s that methadone going to look?
This is some galaxy brain s*it here
Researcher 1: hey let's try to minimize opioids in same day surgery, the US is a huge outlier in this regard
Researcher 2: hey what if instead we gave a F*CK TON of a nontitratable opioid???
The only times I've used methadone are for those on chronic methadone use
Intraoperative Methadone in Surgical Patients | Anesthesiology | American Society of Anesthesiologists


Clinical Effectiveness and Safety of Intraoperative Methadone in Patients Undergoing Posterior Spinal Fusion Surgery: A Randomized, Double-blinded, Controlled Trial - PubMed
Intraoperative methadone administration reduced postoperative opioid requirements, decreased pain scores, and improved patient satisfaction with pain management.

Not even in spines? It's demonstrably better in spine cases than remi/dilaudid, and will at least let you cut down on intraop remi use and NMDA antagonize to oppose OI-hyperalgesia.
These data show that there are no immediate postoperative complications, and these patients were followed for weeks + postop even at home and they used less opioids, were more satisfied in house and after discharge. Yes you may know that methadone is empirically "hard to dose", or variable in terms of pharmacokinetics, but these data show that the danger is perhaps less than you think - none of these patients had postop depression!
Also, the opioid is titratable, as the study that I first cited showed nurses dosing methadone at 2 mg increments in the PACU. At low doses (as seen in the ASA paper), it behaves like morphine and is short-acting, depending on where you are on the analgesia and apnea response curve.
The data doesn't lie. It may feel unsafe, but it's clearly obviously beneficial - at least consider it for patients who will be admitted for 1-several days (especially your spine patients.)