I am trying to find out if I can include closing costs I am paying on behalf of the buyer in my capital gains calculation.  

Quote from @T.

Best and Safest Areas to Invest Near DallasWhen considering areas to invest in near Dallas, especially for house hacking, you'll want to look for neighborhoods that have strong growth potential, good schools, low crime rates, and amenities that attract renters.

A Stanford study revealed that over 75% of the ADUs built in San Jose between 2016 and 2020 did not have a permit and are therefore illegal housing units.The lengthy permitting process, high construction costs, and shortage of tradespeople are some of the factors motivating property owners and contractors to take on the risk of building, renting to tenants, and/or housing family & friends in an illegal unit.

And we also need to distinguish between for-profit room rentals and cost-sharing roommates, which is a big can of worms that I don't want to debate.

The low entry price is tempting, but my opinion (usually unsolicited but not this time!) 

What are your daily carrying costs and how long will it take to evict them if they dig in their heels and make you go through the whole process at the end of which you're damn sure not getting a broom swept house anyway?

There have to be thousands of experienced operators scouring the planet for opportunities to buy low and create an outsized cash flow the STR biz.  

Do you open an account to escrow your tax costs or is there another way?

It is the constant, recurring cost.