Hopefully this makes sense, but sounds like you are got caught in an assessment when you purchased.

But i was able to achieve the elusive infinite return on a majority of my RE and all of my investment RE that I purchased prior to 2020.Infinite return has the benefit that the finances are not the hindrance to scale.  

Determine if the area can support new construction.

And even it's SF when you purchase it, again because it's not 100% MF including the county/city classification, you can use rental income from both units to help you qualify for future investments.Option #3 is something to use only when you're not willing or able to move into the property.

The investment city determines rent growth rate, appreciation, and income longevity.What determines rent growth?

To determine price range, the first step is always figuring our how much you are pre-approved for; and that can vary significantly when you are looking at multi-unit properties because of the additional variable of rental income that can be included in qualifying.

I would try to subscribe to Angies List to determine a suitable mortgage company.

I strongly advise anyone purchasing an old house to flip to ensure they have a clear understanding of the condition of the home's drainage system.

The second option was to do a Construction to Perm Loan inclusive of land purchase. 

Just like when evaluating a potential purchase you should be performing the same due diligence with rents.