Otherwise that would be a fire/building code violation pretty much anywhere.

Maybe it balances.CA has recent water heater regulations that resulted in cost to code using licensed plumber of $1200 for a decent water heater and installation. 

These approvals can take more time (zoning, design review, subdivision platting, plan check of buildings under more stringent building codes), most all of which you'll skip on a rehab. 

I'm looking at buying a 24 unit multi-family property in Houston, in the zip code: 77090.

These are complex homes built to the California Building Standards Code that require installation and finishing to meet the regular California Building Code.Pedro's solution of trying to contact the manufacturers directlyThe manufacturers of modular homes (almost as a rule) don't sell directly to homeowners, so this is really a pointless loop that he is sending you on. 

I'm thinking of starting a lease to own initiative in the 53206 zip code sometime early to mid next year.  

Call the Economic Development committee and you can gain more insight with respect to what I just mentioned and the zip codes that would be in your best interest to stay clear of.  

I want to automate my google sheets using coding/scripts that will sync with all my Google apps to flow as smoothly as possible.

You can rollover any amount from one plan to another and earnings within a plan do not have any coded limit.  

My highest priorities are: Safety, code, and opertions...things should work as designed.