So, your business grows.

I don't believe you need many to keep you busy.

@Gabe Knowles pretty much what @Travis Biziorek said.One of the best ways to succeed in this business is by hiring experts and learning from them so you can do it yourself the right way going forward.Trying to do it yourself and learn as you go, will usually cost you WAY MORE!

I am putting together a business model to convert a single family home to this type of facility and have an idea of the qualifications to get this running.

Any construction will come with LOTS of permits.I don't know SLT market, it's CA and im in NV, but I've helped more than one person sell in Incline and buy in Reno because the numbers work better for them.I suggest you look into property taxes, and tenant protections of NV vs CA. 

My only concern is what if they close shop or sell their business?

So I have this idea about starting a rental business.

It's just the cost of doing business.

Yeah probably not a good idea to advise or try to procure a situation getting your client into an illegal business operation, especially on a public forum.

Which will bring plenty of other investors and general business to the area.