Even if the dog is a service or emotional support animal, the reasonable accommodation clause in the ADA allows you to deny applicants if your insurance will not cover the breed (even in California!). 

It sounds like the person is already a tenant and if that's the case, you can ask for credentialing, such as a Doctor’s note to validate and verify if it’s a legit medical need, if you cannot confirm the need then you can deny the accommodation. 

All they do is pull up info on sales prices.Well if a 3 br house that sold for $200,000 and would typically rent for about $1500/month in an area where land is cheap but rental demand is strong and where small bedrooms in shared accommodation houses rent for $500/month, now has a rental revenue of $4000 a month I would think it would definitely be worth a lot more. 

I've lived in shared accommodation and never has the common spaces been a problem. 

By having all your rooms fan out from a center kitchen and bathroom on a shared accommodation floor you minimize hallways. 

Thankfully there are lots of shorter people that need accommodation too!  

So it would need to be marketed as shared accommodation, but taken to the max. 

So you want to allow the borrower to have you do construction on the home and then you will in turn raise the purchase price to accommodate the construction costs so that they are financed instead of coming out of the buyers pocket?