What's his schedule like, can he agree to do rideshare, food deliveries, or a second job on his off days to guarantee rent?  

You are the master lease holder.

In states where "source of income" is a prohibited discriminatory factor it would be illegal to only show voucher holders the rental. 

I found this on TREC and sent to my current broker, but they still will not post open house on the MLS: https://www.trec.texas.gov/agency-information/rules-and-laws/trec-rules§535.4 License Required(g) Unless otherwise exempted by §535.5 of this chapter (relating to License Not Required) and §1101.355(d) of the Act, a business entity owned by a broker or sales agent which receives compensation on behalf of the license holder must be licensed as a broker under the Act.§535.5 License Not Required( c ) A real estate license is not required for an individual employed by a business entity for the purpose of buying, selling, or leasing real property for the entity.

I just came across one of these near me, but I believe it is being posted by the lease holder. 

we just bought an underpriced piece of land that was unentitled and had high upside in Franklinton in Columbus Ohio. a non profit owned a plot 4x the size an Called us only after our project was announced and asked If we'd buy their site. we gave them 4 different ways they could work with us and their realtor wasn't experienced enough and neither was their director of finance. the bought it to put a food pantry and couldn't because they can't develop. it's a mistake on their part to purchase land like this. their funds should have been used for other reasons.

Second position lien holder?

You could rent it to a food truck to use 1x a week for $100 a day or $400 a month2.

I was told this is the way.However, on a property that I bought 2 years ago, the mortgage note says that if I transfer the deed over to LLC without their permission, they may demand full payment of the loan immediately.I am now trying to get them to give me something in writing that it is okay to transfer the deed to LLC.As for insurance, my broker says the LLC cant be the policy holder, otherwise, lender will foreclose on me.

The Whole Foods/Trader Joes/Starbucks principle works as well.