You can convert the property to MF after acquiring it though.

Interesting to see how feasible this will be. 

I’ve heard different things like taking a Fannie Mae loan out then converting it to a LLC and the likelihood of triggering a due on sale clause is minimal.

Or, in Providence, RI they took the oldest indoor "mall" (Arcade) and converted the second and third floors to apartments.  

I will be converting it into a 8 bed 3 bath property.

And I had done with Allen recommended when I converted my first LTR to MTR.

This is one of my old homes, nothing of a house, the garage was converted to a MB, it sold in like 3 days cash, INSANE price.  

You also tend to get more frequent and better feedback than with an STR, if you treat your residents well.The last quadrant, unnecessary but not obviously so, is usually as a result of either converting an STR to an MTR or from remodeling above the standard needed.

In the event my landlord is interested in selling, I was wondering if I could add value in the short term by, say, converting part of the garage and/or covered porch into a bathroom and maybe a bedroom (currently 3 bed 1 bath).

But if so, you don't have to convert your LLC to an S-corp (or create one) in December.