Signed with PM March 21st. 3 out of 4 units are still occupied with only one tenant paying rent and utilities ( Im unsure actually if he's paying all utilities). 

As long as they are going to occupy one of the units, you can get a very low money down option for loan if you are co-signing.I have a 22 and 21 year old so I understand this.

These are double wide homes that would be attached to the permanent foundation (on owned land, not in a park) and that the investor would look to sell right away to people that would occupy the homes as their primary residence. 

Leveraging an owner occupied loan locally most of the time will take far less cash. 

I would never do a project like this with a tenant occupying.

The property is owner occupied, with no residential renters, and no commercial renters, what type of property insurance is needed here? 

Unless I think I can time the market, I am going to keep deploying my cash in something better than that.I am also bearish on treasuries, which I think will generally see yields rise (and values decline) on anything with longer maturities (yield curve normalization and long term downward pressure on the ratings/"safety" of US gov't debt).All excellent points- I agree with you on assumable mortgages, but I think the challenge is that most of those are owner occupy and the banks typically won't allow them to be assumed by investors.

I am targeting more vacant and non owner occupied houses that are not listed on the market, is this a good idea?

For example in many jurisdictions I can STR units in a duplex but cannot STR an ADU (some jurisdictions will let you STR if you owner occupy).

There is verbiage in Section 11.131 of the Texas Property Tax code that states that exemptions only apply to residence homestead, defined as the portion of the property that is occupied as a primary home.