If I rollover 100% of funds from a tradition IRA (both contributions and earnings) into a checkbook IRA, Can I buy a RE property with my checkbook IRA funds regardless if the funds are from earnings and contributions?

Again, your time horizon is the key here adjust with that in mind.The timing is impossible you can look for signals but still hard to pick the bottom.So, for me I pick companies that have good balance sheets just because a company has gone done does not Mean buy it, could mean it is on shaky ground could roll over and shut down.So, I pick blue chip divined stocks that have low debt good business model.If you are not going long then good luck this recession may be short or could drag on keeping profits low and sluggish, punish the stock.

Once such account is established, you can rollover funds from your current IRA and new IRA would be the owner of the property.

@John UnderwoodTo be clear, if there is a legitimate Coronavirus impact, using this method to liberate the funds from a current employer plan to effectively "rollover" funds is not a concern.  

One with pre-tax funds from a 401k roll-over and the other with post-tax funds from a ROTH IRA. 

You just need to work with qualified counsel to ensure you understand the rules.An entirely different approach that may appeal to you is to establish a Rollover as Business Startup.  

Upon leaving the company, you first roll your 401k into a Rollover IRA.  

In-service roll over wasn't an option at my previous company so I just changed jobs and rolled the funds to a self-directed account.

After reading your comments, I'm wondering if I can roll over my old 401K into my current 401K and then convert my current 401K to either a self-directed IRA or self-directed Roth IRA - enabling me to "invest as a money partner in deals".  

@Todd Magin You can roll over most types of retirement plans into a Solo 401k, except for a Roth IRA.