I'd just really like to avoid buying a home in a nightmare neighborhood just because it matched my price point.

In most cases, the tenant will move out as soon as you start the process in order to avoid court.

., multiple site visits on an anonymous basis), apply analytical stress testing to pro forma financials and avoid certain categories of properties altogether (Senior Housing, Oil & Gas, etc) to ensure that all underlying properties held by the respective DSTs are prudent investments for folks who are not experts in making risk assessments for these larger operations. 

I feel like 20-something y/o's are being dupped into it as well, and want to avoid that regret of throwing money in there just because every traditional W-2 employee thinks it's the holy grail for retirement.The reason why I leaned towards not using their plan is:- I plan on retiring by 40 and imagine there's a big penalty for taking money out before 60.

Yes, I do track my net worth properly not because I need to report to someone but if you consider yourself as an investor, it is always the best to know your financial aspect as properly as possible.

I heard I should completely avoid national, but I'm not sure what other criteria I should be using for my search.

I don't know that it will change my eventual decision on avoiding SoCal, but definitely will keep an open mind to the advice of experienced folks like yourself.  

Because it was my homestead until the end of 2017, if I sell by December of 2020 I avoid capital gains taxed (because I will have lived in it 2 of the last five years).

After that you will need to structure your investment (in all likelihood, LLP to avoid to double taxation that comes with LLC). 

I don't think your strategy involves delayed financing at all, rather it is a way to avoid delayed financing.