If you're looking for additional safety, you could even split some of it to be invested into conservatively underwritten debt, so that if things go badly you can foreclose and recover some or all of your principal.

rent * 50% = NOI - debt service = cash flowthe 50% rule is a guideline and not a rule.

The less debt the better especially on a primary residence in my eyes

My experience as a one time squadron legal officer and frequent renter is that when a military member moves, they often refer another to your place.

You may have something written in the loan documents about the minimum ratio (ie. debt service coverage ratio, times interest earned, etc) that you need to meet in order to comply with their terms, so make sure you have the line items in your financial reports needed to calculate them.

As someone who has experience in this realm (however, do not take this as legal advise by any means), the cleanest way to do this is form an LLC. 

I have a friend looking for an attorney to help with the legal aspects of raising investment funds for the acquisition of a building for a gym in the DFW area.

You don't want to spend the little money you have or worse (go into debt) to pay for a guru class that doesn't work. 

In my case I’m legalizing several existing inlaws.

For 10+ years I've made most of my income from internet marketing (I've never had a "real" job), and I've done lead generation in some very competitive niches (home security, debt consolidation, etc.).