I know my employer 401k has limits on the amount of the loan I can take are there loan limits on self directed plans?

I was so "into it" that I registered and started an investment club - the Boise Stock Exchange, where I taught my techniques to others (for free - it was a meetup group).I was met with skepticism from other traders, simply because they had; never traded futures, had heard horror stories about trading futures, knew nothing about how to trade futures, and could not fathom the amount of risk I was taking or the leverage ratio I was employing.  

In our area(s) and experience (which feels more limited as time passes) a rooming house serves a distinct clientele:  a) university students (perhaps a sub-population such as international students); b) work force for a major employer (factory, refinery, mine, hospital) or c) those on the margins (those one step from the streets, the mentally ill {as governments have closed most of the traditional homes and care facilities}, the addicted, etc).  

Every investor's situation is unique, and the mix of available capital of both qualified retirement and non-qualified types, employment type and income, investing expertise, age, and goals will be just a few of the factors that one would need to consider when designing a strategy.A fee based certified financial planner would be the best resource for making strategic decisions.  

The rental market here continues to run along fairly strongly, with military, healthcare, and industrial employment being primary economic drivers.     

I've made my biggest profits from SFR's, both flipping and holding, but I'm not otherwise employed and do all my own work so I have about as much control over things as is possible in this field.

(personal) I know Facebook is a key marketing tool but my current employers follow me.

Yes thats - 200-300 pages of financials, letters of reference, pictures of (or interview with) your dog, letters from your employer, bank and current landlord and $500-$2500 in BS fees that you never get back even if they deny you the apartment.  

I am a mechanical engineer, employed full time, with excellent credit score, so I'm thinking a low down payment FHA loan is a good option. 

Depending on your employment status, marital status, etc you may be able to allow any long term capital gains to not be taxable.