(Sorry for spelling issues in the follow post! I am on a new tablet and haven't gotten the hang of the much larger keyboard).
I will preface by saying I am new to this game. While I have been spending at least two or three hours a day for the past six months reading and studying the topic of real estate investing, I have not yet reached a financial position to execute a deal. As a a stark newby with no firsthand experience, please understand that my advice is not necessarily the most sound. Also keep in mind that I don't know your personal finances! There may be more that I am simply unaware of that would completely invalidate my thoughts on the subject.
That said, here is the situation as I see it. You have a property here that you are apparently already in a bad position on. If you are unable to afford the mortgage payment for any amount of time in the event of rent delays or unforeseen complications, then your margins are dangerously low. What you have is not an investment, but a serious liability! You had mentioned this was supposed to be a temporary position, and I can understand that, but it seems that (despite the great work you've done in finding fair market rents and being a considerate landlord), you have a property whose numbers just don't seem to work. You make your money when you buy, as they say, and it sounds like this buy may not have been a good one.
Potentially worse than the cash flow problem are your concerns about selling the property for enough to cover what you owe on it. While a major renovation/upgrade like finishing the basement may raise the value of the home and allow you to theoretically improve the cashflow, that's even MORE debt you would have to overcome on the sale on a property that you are already potentially underwater on! Not only the total debt would go up, but your monthly payments. If you can't afford the costs of the home withoutma tenant as-is, then you would be shooting yourself twice if/when you do eventuslly losr your tenant and have a period of vacancy.
Were I in your position, I think I would take a very thorough look at the books. Determine what price points I would have to reach to break even, and/or how much equity I would have to build to break even as a result of mortgage payments or improvements before making any decisions on further renovations. Don't forget to factor in closing costs on the sale and the additional debt built by the suggested renovations.
Good luck! I hope this has been somewhat useful in helping you to analyze the situation and make the best financial decisions for yourself! Again, I am still strictly an armchair landlord, and likely will be for another year or so as I work on establishing myself as a real estate agent, so please don't hesitate to consider other people's opinions on the matter. They very well may have greater insight than I.