Short Term Rentals take a lot of time and energy.

Even though it may seem far from your current location, the potential for rental income and long-term appreciation can make it a worthwhile investment.In your case, if you are concerned about managing the property from a distance, consider building a network of reliable professionals in the Corpus Christi area who can assist with property management tasks, such as property maintenance, tenant screening, rent collection, and property inspections.

There's nothing wrong a slab foundation in fact they are more energy efficient typically. 

This increases the property's value and can allow you to charge higher rent, improving your cash flow and the property's appraisal value for refinancing.Rent: Lease out the newly acquired and rehabbed properties, preferably to reliable tenants similar to the family you currently have in your townhouse.

Hint: look for a solar architect, who acts as an adviser and works for you and audits the installer project proposal.Many states/utilities are no longer allowing net metering (kWh for kWh) and use instead all kinds of payback schemes (e.g. if you over-produce, they will gladly take your kWh for 3 cents and graciously allow you to take it back at night for 22cents - end result being, if your system is not properly sized, you will be producing energy for the utility and never recover the costs of the installation).

Out of state can be difficult if you don’t have a reliable team in place.

I'm shooting to create enough passive income in the next 5 years so I can sell my current businesses and refocus my energies on creating a comfortable life for my wife and I.   

I do believe it's probably a question of 'when', not 'if', but at the moment, I don't see how that prototype saves any money, considering running wiring & plumbing with solid concrete walls (you'd likely furr over them with conventional stud framing, and would be building 2 walls instead of 1), meeting energy codes in different climates, envelope tightness, and satisfying aesthetic preferences. 

Any recommendations for reliable general contractors in the area?

I understand what motivated sellers are and when you do, you will see that you CAN NOT target them.So I focus all my energy into being the easiest person ALIVE to be found to a very specific audience: People that are willing to sell their house below market value".THAT is how and why my wholesale deals reach 6-figures+ consistently.Want more direction?