If the asset manager sees that there is a missing signature, the selling agent will be notified about it requiring them to amend the contract.  

Some people make mistakes during their lifetime for which they can make amends, if we allow them the opportunity.

To get the deduction for the interest expense, you will need to file an amended return.

If I came at them in a couple weeks after I couldn't find an Investor and suggested them carrying a note we could amend the old agreement or just tear it up and make a new one?

The mortgagee can agree to allow for the assumption of the loan by the grantee but that would require a written amendment to the note whereby releasing the original borrower (grantor) and obligating the new borrower (grantee).  

You can just have an amendment to change the rental amount and everything else would remain the sameYou can also use forms from the Texas Real Estate Commission website

But if it gets amended and cleaned out to allow more foreclosures in the next 6 months that opportunity will fade away.

Write up an amendment to the contract giving you more time to remove conditions.

In addition to any other penalties imposed under R.S. 37:1455 and 1458, the commission may require that any person engaged in real estate activity without a license return any fees collected for engaging in real estate activity.Acts 2003, No. 713, §1; Amended by Acts 2006, No. 343, §1

LLCs can provide taxation benefits, ease of distribution of profits, and flexibility when you want to joint venture, or have hard money lenders, or want to amend the agreement, etc., which is not quite as simple with a land trust.The only two reasons I would ever suggest a land trust instead of an LLC would be, as people mentioned above, privacy, BUT, (1) that can be achieved with certain state LLCs, like Wyoming or Delaware anyway, and (2) most investors honestly don't care.