To not charge for it is to cover a cost that any tenant for the entire yard would need to address themselves...from the tenant side they can say that including it reduces their useable area below their 3 Ac gross...neither is right or wrong, it's just differing perspectives on what is best for them. 

It is usually reduced leverage but an option! 

Completely eliminated noise complaints from the lower level and reduced utility costs.

Assuming you go the HELOC route, another option to reduce your costs assuming you have decent credit is to look at credit card balance transfer promotions.Back in 2003-2004 I had HELOCs on my investment properties and interest rates were increasing.

Imagine making millions of dollars over the course of your career and then having to pay 30-50% every year to uncle sam instead of compounding that cash over time.This is exactly what real estate professionals have learned to mitigate.To reduce their taxable income, they just buy a building every year, do a cost seg, and use depreciation to reduce their tax liability dramatically.Their personal wealth snowball grows much larger and much faster than their W2 counterparts who give most of their money back to the government each year.Following this strategy as a real estate professional is one of best ways to end up with a much larger net worth at the end of your career.

Reducing risk requires at least some time spent in research and involvement in a deal.There are many other things you learn along the way as well. 

Consider the aesthetics, privacy and reduced contact with passers by if there are animals involved.  

The best thing you can do to reduce evictions is keep your price point high.

At this point since it's after the fact while not totally correct; you may explore adding the missed asset/basis amount as a selling cost to just reduce your gain. 

Factor in capital gains tax (unless using a 1031 exchange) and depreciation recapture, which can reduce your net profit.