The Seller is not interested if there is immediate tax payment.   

Based on what you described the LLC is likely the tax-payer on title.

Most other states assess property taxes annually on the fair market value of the property whereas CA allows for this lower property tax payments compared to the FMV if the property has been held for a long time. 

It’s not enough to cover one quarterly tax payment.

Further, he's using an @gmail.com email address—don't get me wrong, I run my RE business through my primary @gmail accounts set up for the LLCs, but as a legitimate tax-paying lending company? 

It's very easy to book a quick flight to Mexico at the taxpayer's expense and go and check on what's going on the ground.

A benefit of this method is that by grouping the activities, it allows you as the taxpayer to treat the activities as one when applying the 7 tests to determine material participation.

If you create a new partnership then you are not meeting the same taxpayer requirements of the 1031 exchange. 

It was previously assessed @ $250,000 with a $1,500 yearly property tax payment.

Obviously the gain increases significantly the longer you defer your tax payment.