@Kevin Hoover, with certain types of entities it is possible to contribute property to and distribute property from that entity without triggering a tax event. 

Don't over think this, pull the trigger actions create results. 

But if they don't willingly make the payment your only option would be to sue, and they have the upper hand to let the lender know about the sale possibly triggering DOS.

Very few people operate their LLC correctly and therfore this just gives them a flase sense of security.Moving into a LLC can also trigger the due on sale clause.

Ensure that the mortgage is assumable, and confirm that there are no due-on-sale clauses that could trigger the full loan balance. 

You would only pay taxes on all passive investments in a traditional SDIRA at distribution, unless you have a mortgage, then the portion of the income derived because of the mortgage will be subject to UDFI (unrelated debt finance income) which will trigger UBIT (unrelated business income tax). 

If the $700K sales price is not used correctly to acquire qualified real estate, the exchange could fail, triggering tax liability.Future exchanges will depend on the total value of the replacement property acquired, so entering syndications could limit flexibility.

BUT I have also heard that it could trigger a due on sales clause, bringing the note fully due at any moment.

Personally, in this market, I would work on saving up and really doing my best to find a great opportunity and pull the trigger then.

The boot amount is taxed as capital gains and may also trigger depreciation recapture.For example, if you sell a property for $500,000 with a $300,000 basis, resulting in $200,000 of gain, but reinvest only $400,000, the remaining $100,000 is taxable.