Either go a year vacant, or repair with realization that there is risk that sale is over turned.  

The board can try to implement a rule restricting rentals without getting feedback from owners, however it is susceptible to being overturned in court.

Multiple news reports are stating he has declared that he will overturn large portions, if not all, of Dodd-Frank.

During that 3 years they make no efforts to locate the owner, they usually send out a letter (would go to the house address) right after the sale saying you MAY have funds to claim.Since there is no redemption in PA, almost all Tax Sales are overturned on notice, as @Ned Carey says. 

The law is almost certainly illegal and will be overturned at some point by a higher court but it will have succeeded in making the City an unattractive place for investors.  

And Airbnb could also increase rents and push out current permanent tenants for short term residents and tourists.Maybe the issue won't be enforced or maybe Airbnb (after having been recently funded significantly by Google, and being no stranger to lawsuits themselves) could overturn the decision.

Maryland has something called "post sale exceptions" which can be used to overturn a foreclosure sale.

They really only make sense if you are paying all cash and have deluded ones self into thinking theyes will help overturn TPs rent control as people have been trying to do for decades now.Your rent is likely on the high side then too in your estimate

You have the right to December’s rent, as the owner.Unfortunately, there is no appeal to overturn the mtg foreclosure or way to buy you more time.  

Also What would it Take for him to OverTurn the Deed & Have it in His or Someone Elses Name ?