I like to keep the whole concept very simple so I don't even bring up interest to the seller.

This is especially useful if there is no clear vision or you want to save time.On the other hand, if you have taste and experience in renovations, you can do without a designer and invest the saved money in more practical things: high-quality furniture, equipment or amenities for tenants.I would consider a compromise: order only a concept layout from a designer, and do the implementation yourself.

Her apartment can easily be converted to an open concept 2BR. 

I understand the concept of doing a 11031 into a tenant in common situation. 

The concept is good but do the numbers work?  

We are not talking about the larger concept. 

There are no shortcuts really because it takes time to grasp a lot of these concepts.

Good question, and this leads to the concept of a net tangible benefit.  

First step is determining the viability of your concept. 

Even in a less invasive county, I’d start by scheduling a pre-application or “concept” meeting with the planning or permitting department before doing any work.