There are companies such as Cover that offers a full service ADU deliverable from design through construction completion.

I would also look at the availability of public water and public sewer, if not at the site how far away are those services.

And yes I would recommend my services :) Hey @Donald Hatter!

If a person has to ask, at all, I STRONGLY advise to use a PM service for tenant placement. 

Our experience is that many lenders/servicer customer representatives may not know the protections that exist for those that want to put asset protection steps in place. 

Rather than paying for childcare services from a large organization, we found that it was significantly cheaper to pay for a second mortgage than to pay for childcare.

if he performs a service for you, just pay him for it. 

Usually having a servicing company helps the lender to consider that.  

There are lenders out there spending a ton on advertising with an army of correspondent's funneling them loans and many can very well be one and done borrowers because the loan servicing/construction admin is lousy. 

And if you are need of MTR management services, my company, Island Stays Hawaii, provides premier STR and MTR management services.