Unless you want there to be a focus on the trim, the mud seems like the simpler way to go, and like you said, you can always add trim if need be.

I understand the concept of buying a property subject-to and doing a wrap-around mortgage to the end buyer, would this "wrap" consist of a lease option for the buyer?

This gives pretty in-depth knowledge of real estate concepts, with the ability to work in the public or private sector. 

I would imagine similar to airbnb concept without the hotel approach and more of longer term lease.

I was told that I should go with the mortgage broker that she recommended as the process would be much simpler.

I am in the Baltimore area and was doing some research on the legality of that concept here in Maryland.  

A very unique concept you need to look into

Do you really neeed an official comprehensive business plan, or would you be just as well served by writing your concept, goal on a big white board for clarity and then writing out the steps needed to implement it?  

The concept of wholesaling is foreign, as in, for us to "sell his house before we even buy it from him", and he has an issue with this.  

For me, the shorter and simpler the better for all parties.Hope this helps.