Again, I know the threat of due on sale is currently extremely low, but maybe the frequency of the due on sale clause being called may become more frequent now that interest rates have risen considerably, and subject to deals are becoming more common. 

Is skip tracing recommended or a particular frequency?

A properly done non-business size color envelope that has a handwritten address and hand written return address gets opened at far greater frequency than a computer printed #10 envelope. 

The electric ones you plug into the wall also work and are based on the same thing using frequencies to scare them off.

And I plan to change the code with some frequency.

@Brandon Hall There are 9 standards that the IRS traditionaly has  used to determine if a taxpayer is a dealer or investor:1. reason and purpose the property was acquired2. lenght of time property held3. number and frequency of sales, usually annually4. continuity of sales over period of time5. overall reluctance to sell property6. substantiality of gain on sale7. extent to which tp engaged in sales activities8. substantiality of sales when compared to other sources of income9. desire to liquidate The taxpayer does not need to meet all 9 or any number.

Each of these, and everything else in the property, require maintenance and replacing at a certain frequency plus occasionally when you don't expect it.

You may even find it's just a really simple problem in a very limited area (like 2x1 feet) that has to do with improper chimney flashing (this happens with extraordinary frequency here).With any sort of competent preventative maintenance efforts, the "good side" is easily going to last you the twenty years you're going to hold this property in your portfolio.

So, ultimately, you are the one responsible for ensuring your IRA transactions are within the rules, regardless of which structural approach you choose - custodian held or truly self-directed with the checkbook LLC model.In some cases where the dollar value is lower and the account is being invested in relatively static assets without time-sensitivity or frequency of transactions, a custodian serving as intermediary can be a fine solution. 

I'm averaging a cost of 12 cents a touch this way and hitting a frequency of 9+ a month.