I need some perspective

In the USA ASPAN is the clinical organization that writes the standards for PACU care. They have very clear standards for minimum staffing and patient to staff ratios. Many managers ignore these standards or use work around a like the OR nurse (who is in the OR cleaning and stocking) is your 2nd RN so you aren't alone in PACU. This is an issue at a lot of hospitals. I would suggest joining ASPAN and obtaining a copy of their Perianesthesia Nursing Standards and Practise Recommendations, then start putting your concerns in writing citing the ASPAN standards of care. Is there anyone else in the chain of command you can go to other than the hostile supervisor?

How do the other nurses on the unit feel about this situation? It sounds like you need to team up to present your concerns. It's harder to ignore a majority group. Pull together supportive evidence such as census data and staffing reports as well as your ACORN standards. If your collective concerns are still dismissed, escalate to your director or chief nursing officer.

If you need to escalate above your manager, you might consider whatever incident reporting system is used in your hospital. Ours is called Midas and is used for events and near misses. The reports go to risk management (hospital lawyers). If they see a report that you are asked to take an unsafe (per ACORN standards) patient load, they will want management to explain how they will prevent that condition from happening in the future.

I won't take an unsafe load and have refused an extra patient a time or two, citing ASPAN standards. It is a risk to say no but I value my license more than my job.