@Josh OteroThe hardest part for me was being flexible with my tenants and realizing all these people are living paycheck to paycheck.

As already mentioned, he wouldn't be able to use rent from roommates to help qualify but based on the numbers you shared there should be a VA option available considering how much flexibility there is. 

Ideally I'd like the ability to invest in individual stocks of my own choosing (fractional shares is a plus), a diverse option of index funds, and ETFs.Has anyone found a great banking option to have the most flexibility with your HSA investments?

Quote from @Zongfu Li: An agent named Mathew Dial contacted me for loan opportunity and told me how flexible and how easy they can provide bridge loan lending and conventional lender.

This can give you flexibility for purchasing or even renovating the next property.

It is flexible though, in that I can roll it into any IRA at any time.

Since this is my only property I do not mind and with my flexible schedule I am able to spend time doing this. 

If I was not starting from scratch, like I did myself, I would buy SFHs because I prefer their long-term flexibility, relative scarcity, and multiple exit strategies to MFH.

I know it's not as flexible as a HELOC but as long as your deal flow is good and the tenants are paying the mortgage you won't come out of pocket for it. 

The 25% has to be your funds.Now, there are non conventional options that would be a bit more flexible but even most of those programs will require at least 20% down with no second mortgages filed on the property.