The strategy that I want to implement is house hack using my VA Home Loan and I want to do a multi-unit (4-plex) if possible in OC, California.

Start with education and network with people who know more about the strategies you are planning to implement.

It's great that you are trying to maximize you knowledge and implementation of tax breaks available to real estate investors. 

I wonder what the legality around it would be, or if there is anything in the executive orders preventing it.

However, if your credit is preventing you from getting a bank loan now, will it be where it needs to be 12 months from now when you need to refi out of that high interest hard money loan when it comes due? 

However, if we try, we will always find worst situations than ours :)I do expect and budget for some bad things to happen, I was only wondering if we can prevent them somehow.

I 'need' one to prevent having 'constructive receipt' of the funds I won't be receiving. 

Why not give the banks time to close these loans in September and then implement 10/1....  

I wonder how something like this would be implemented.

I would say any technology that you can implement to save time on some of the "time suck" tasks the better!