If you do not have data/comps to find out your post renovation value, that ads a huge risk, and makes the move less valuable. 

Also, it is okay to go through some extra maintenance for the short term. 

I'm contemplating this decision because I'm not sure if it would be desirable for tenants to have an extra room instead just a loft area.

After that, I would encourage you to go to your county recorders office / court to request data yourself.

We plan to take all extra income after that and pour it into real estate investing.

Out of the 20 letters I've sent, I've had 1 guy get back to me and we were in discussions but weren't able to find a price that worked for the both of us.The issue is that I only have a few houses on my mailing list so far (just places I've walked or driven by that caught my attention), and blindly searching every street and address # to see which houses are actually legal multifamily will take forever and doesn't seem efficient.I know the data is publicly available, I just don't know how to aggregate it in a way that would be efficient and useful for blasting out marketing mailers.Are there any websites that can pull massive lists of all multifamily houses in my area?

I’d look into historic appreciation data for the area before making a decision.

With this set up, we were able to get a DSCR loan through Kiavi with only a few extra steps compared to an LLC.  

MTR is treated like an LTR from what I understand and I already own a couple LTR's so would rather do more of those than an MTR and avoid the extra hassle of furnishing, etc.  

Have good data and comps.