This is far from an easy business.

I own a 3-unit multi-family with a business partner.

The property is located in the Midwest and me and my business partner have ran the comps, numbers and called numerous property managers, handymen, inspectors and even asked locals on reddit to get a better understanding of the rental calculations and local biases in the area. 

I could probably help out a bit, but I've been super busy. 

For our STR we have a few different types of loans but I would always go with the 30 year fixed because you never know life gets busy and in 5 years a lot can change. 

If the property is being sold for 400k (and I can afford the 20% down) but another 800k min needed for a complete renovation (my personal rough estimate), can I take out a traditional business loan to cover the rest, if I were to purchase in my LLC?

I would love to connect over coffee and learn more about your business!

Since this would be considered your course of business because it is not a one off, you should also look into things like using 3rd party servicers etc. to maintain compliance.If you want to do it right, then yes use underwriters to review the loans and treat it as if you were Wells Fargo originating a loan to yourself.

We are in the "due diligence" phase of our evaluation and as business owners ourselves, we make decisions slowly and deliberately(over months/years). 

This property must be used in a trade or business and held longer than 1 year.