Includes Upgrades such as New roof and hardwood floors (2016), 2019: Upgraded plumbing, reglazed all bathrooms, new bathroom floors, new vanities , new fixtures, new toilets, all new appliances, multiple zone heating and air conditioning mini splits, new water heater. 2021: upgraded electrical panels, added basement heater to prevent pipe freezing in winter...

You have between $4-5.75M of buying power depending on the leverage you want to take on. 

The trades like electrical, plumbing, hvac must be licensed but not a general contractor.

Same thing with the SFR investment do a Cash out refinance have the money "Liquid cash" reserves on hand to offer a more aggressive purchase power and a higher PITI reserve fund.

Dan Powers - New Western Acquisitions

I use QB in my "day job" and it's far more powerful than what you need to self manage a portfolio.

(These are not metered out so gas/electric and water/sewer is killing the cash flow).  

If you are having to do serious electric , plumbing, HVAC, or layout changes, it probably won't work out well. 

I am thinking of buying an empty lot of land( which would already have electricity/gas), setting a slab, drilling a well, and then putting a mobile home on the property.

It'll increase your purchasing power a bit.