I have been in the same kind of situation as far as loans are concerned. Over borrowing won't qualify me to get new loans.
However, think this way:
1) Cut loss just like you bought a bad stock. You have to sell it even thought it's bleeding.
2) Improve your overall cashflow by reducing the loan payment and maintenance cost.
3) The vacancy may come back before too long. It's good timing to sell when it's fully occupied.
As your portofolio grows, you will use rent money to invest and reduce the liability on loans. That's another reason to invest in SFH with smaller capitol.