I think you benefit most by moving to higher income areas earlier in life, then when you retire, after you've amassed what is a large amount of savings, moving to where the cost of living is cheaper.

FYI, I am on the same 15 year Am retire around 50 plan. 

What I want out of this is financial freedom to build wealth long after I retire.

As far as Penny Stocks are concerned, I have a retired Miami Dade Fireman/EMT friend who bought up to 100,000 shares of a 2 Cent Penny Stock with the recommendation of his Broker.

I've mentioned to the seller that I would like to get more properties off of his hands (he is retiring) but i do not have the funds to do so.

Literally every 401k I have seen has this ability, but obviously someone somewhere at some point used a city/county/state employee retirement account or pension fund that you can't pull funds from to prevent foreclosure, and then that person sued some bank for 'predatory lending' when they couldn't pay their mortgage, so now on our end we all have to cover our you-know-whats and get the documented proof that your particular exact retirement account allows you to pull funds to prevent foreclosure.

Your retirement is also very important so I'd suggest that you save somewhere around 10% of your income for that.

This is why the 1031 has a place in the right transitional plan.I like your foresight and thinking now about how to strategically place your assets so they can provide the benefits listed above while not sapping your energy in retirement is key. 

@Kevin Reed With the retirement community you might have less turnover, but the HOA is expensive.  

I plan to take the brokers test when my 4 years is up so I'm not in trouble if my current broker retires or moves etc.