I would then plan to use this forced equity (since I plan to buy a fixer upper) to invest in another home.I have been constantly reading to househack right into the MFH, but this may take some time for me to acquire the money and purchasing power.

Make sure you get a rock solid lease in place even if it is just for 30 days.

But it does make me wonder...  

You work a stable job and make $5K a month.

I see a lot of ads when reseaching online that make it sound like my scenario is possible, but I've been skeptical.

I am a private money lender. 

Yes, you have more than one option: You could definitely look for private money, but if you are planning on keeping it as a STR, you might want to make them your partners in the deal.

Together, it worked out for me as their combined income allowed them to always make rent. 

Make sure this is factored into your calculations for whether or not DTI works.

My goal is to get my Mortgage payment below $490 with less of my money involved in a DP.