Go the traditional route to avoid points and fee's.

I would raise the post above the new cement and even then avoid having wood touch the cement as the bottom will simply rot over time quicker if they are in direct contact. 

"Higher risk" seems like what I want to avoid right now.

This allows the purchase to act like a normal purchase transaction and avoids all the construction complexities. 

The best way to make the numbers work is to limit the work to cleaning, paint and carpet and avoid expensive projects like roof, windows, replacing plumbing and electrical systems, driveway etc - as these take huge amounts of capital, but will typically not drive up the ARV by much.

You might have to get a plot plan to see where your land ends to avoid any legal conflicts in the future. 

I have excess earnings after expenses and my accountant advised to spend this cash on a property, vehicle, or 401k to avoid paying taxes on it.

He guides us how to avoid co-mingling funds. 

We are selling an existing rental property and want to do a 1031 exchange to avoid the tax consequences.

I can connect you with some great property management companies in this market for more accurate income projections and let you know which to avoid.