I can only assume the final sale price would be some discount from the ARV equal to the rough rehab costs that backs into a reasonable rental or sale return.

Sell and take your primary residence portion tax free and A. pay the tax on the rental portion B. do a 1031 on the rental portion but buy less since the sales price of the rental portion is less.C. do a 1031 on the rental portion and buy two properties instead of one to equal the sales price.D. do a 1031 but buy less than what you sell and pay a little tax.Break out the Excel sheet :)

and "does one plus one really equal potato, or is what the computer spit out complete nonsense?" 

. : You bought a 500K house for 430K House Appraises for 500K - 25% Equals 375K. 

Your assets minus your liabilities equal your net worth in general.  

big national lenders cannot... equal housing laws.

Best practice is to establish your rental criteria and communicate that rental criteria to all prospective renters, equally.

It would take more than five years of rent to equal that offer, not counting vacancies and upkeep and blah blah.

They can both be equally gross and destructive. 

The food truck busines is a cash biz, so nothing odd about him paying personal bills with cash.....all else being equal.