Do you consider this a red flag to invest in Cali?

These can collapse or roots can enter them.

Well here in the part of Georgia I live in, we have that famous red clay but unlike some clay, it will perk adequately in drain fields.

Red flags to avoid?

At the same time they red tag abandoned homes that aren't safe and make the owners tear them down in hilltop.

There are just too many red flags here (including your inexperience) for this to be the right first MHP deal for you.Attend F&D's bootcamp (www.mobilehomeuniversity.com), get educated.  

Lots of issues to consider like title insurance, due on sale, comingling of funds, IRS red flags etc. 

Quote from @George Red: @Timothy Burns fingers crossed for you... sounds horrible.

Most investors try and take advantage of the Primary Home, Secondary home program without concern.When you buy too close in proximity and too soon in terms of sale date you trigger red flags. 

Use the product "Red Guard" before tiling and be sure the returns and sills are prepped this way.