I would say that the most important lesson I've learnt so far is to implement systems and processes.

Mainly, the systems implemented are fascinating (VA, automated offers, etc.)

Will implement this!

I would still implement the house-hacking strategy, just on a 2 to 4 unit instead.

Since you are buying with cash and you have a partner, both are solid reasons to implement asset protection.

It is up to the individual buyer to objectively weigh ALL of the factors including mortgage costs and interest, alternate investment returns, tax consideration, amount of time needed to implement and manage the decisions and personal investment goals.

Any investor considering the use of such a plan should be sure to educate themselves thoroughly and work with professionals not only for the basic acts of implementing the plan, but more importantly with regards to the proper usage of the plan and developing an investment strategy that will meet their goals while remaining in compliance with IRS guidelines.  

Keep in mind that the reason lenders are so stringent on their conventional loan requirements is because they're meeting certain criteria needed to, potentially, sell your loan on the secondary market.  

Any software you use, you need to setup, implement and be diligent in using it.

Need to investigate the options, please feel free to share strategies you have implemented.