This would require us to either fillng in the crawl space or lifting the house a minimum of 6" which was out of scope of the project, never told to us until after we signed the loan.

Since you only received the quote verbally and not a formal Truth In Lending (TIL or TILA) you really can't compare the two as you may be comparing apples to oranges.

These costs can add hundreds into your budget each month and must be factored in to compare apples to apples.

Compare apples to apples.

Most people asking likely fall into the category of wanting to take advantage of your experience so they don't have to lift a finger.  

Just the cash flow savings themselves would allow me to buy a house once a year, and I'm not paying the transaction costs as a buyer...Again, in your example, you're comparing apples to oranges.

Then, if it is a nice neighborhood as you describe, it should be easy to manage as a rental with a solid middle-class family as tenants and rent increases should do some heavy lifting for you over the long haul if it stays nice and there is as a result significant rental demand.Otherwise, I'd wait until you are ready to move then buy your replacement property and move, but not before with those numbers.

I'm considering lifting one of the houses to add a lower apartment.  

It's just a random metric to be able to compare multiple, different properties on an apples-to-apples basis.  

The PR of the estate then signs the deed, This is not as hard as it sounds and an attorney can do the heavy lifting.