Definitely consult with your CPA about this as you may have specific situations that didn't come up in your post.Generally, there is an advantage to running businesses like property management or wholesaling through an LLC taxed as an S-Corp, as it can save you social security taxes (your CPA can run the numbers for you along with a more comprehensive tax plan).However, it's usually a bad idea to hold rental property in an S-Corp, so you probably wouldn't want these two revenue streams (rental and wholesaling) running through the same entity.Let me know if you have any questions!

But what if a bank could give me a secured loan up to the amount of my documented contributions, while also holding that same money as collateral?

We have 1st, last, and security deposit. 

Granted, because of this, there are a lot of "miners" here so you'll have to be creative and consistent.    

@Grant Hibbert Hey Grant, thanks!

I am concerned that because of my age and lack of money I will not be taken seriously by banks when trying to secure a mortgage.

@Grant Rothenburger yes but if this poster has a track record of flipping in the past they may be able to get it a bit easier than someone who is just starting out. 

In a perfect world my virgin purchase would be a duplex-quad, one unit of which I will live in until I can secure my second deal.  

@Grant Rothenburger Have you worked with Lima One?

I see no way that they'll grant you any kind of permanent waiver.