However as others posted above the paper copy ( of the recorded deed) once actually recorded is not an important document to keep on hand as its of record and in many counties it takes 30 to 90 days or more to receive the original back in the mail..

But you need to show that you had the intention with some documentation, like a signed lease for the property, newspaper ads, craigslist ads, photos of for rent signs on the property, etc.And unless you do another 1031, by selling the 1 property you'll owe taxes not only on the 1 property sold but also a portion of the gain from the first property relinquished in the 1031.An alternative would be to suggest to the buyer a rent with option to buy or some other mechanism to both show rental income as well as deffer the sale until year(s) down the road.

Are there any other things we should be doing to insure proper documentation?

If records are online you can also look up recorded documents for that specific property.  

Common sense would say she already has these documents on hand from the seller for you to review.If she does not have these and will not allow a contingency...RUN

To ensure it is a legitimate tax deduction - what loan documents  between me and my overseas private lender are required to satisfy the IRS.

I would assume a type of document? 

Generally, they will overnight (via Fedex or UPS) the documents to you.  

If you have a deposit you can probably find enough damage to document and keep it all. 

You as an investor, especially in a sandwich lease may choose to record your memorandum of option or other similar document to protect your interest and potential equity in the property, but you're unlikely to record the option with your tenant buyer.