My question is if I'm not a real estate professional, but own an STR that fits inside the STR loophole. 

Don't think you would be covered properly with out an attorney too many loop holes.

I like to think that where there is a blind spot- a loophole is waiting to be found.

Is there any legal/accounting interpretation/loophole which would allow for that sale to be considered a "capital gain" so that I can utilize my stock losses as an offset?

If you want to do anything that is not bright line, specifically spelled out, you will need a smart lawyer who will figure out a loophole that will stick and have the ability to argue and make it stick.Anyone claiming they know how this will play out over the next five years is full of bovine excrement.

Second, the bill states "residential" properties, which may allow for a loophole for multi-unit properties of 5+ units, which could be categorized as commercial properties.  

We run a real estate business with a lot of airbnb-minded clients and the number one thing we tell people to be is super clear with their insurance on what is going on and the legality behind it, so that you know you are totally insured and some loophole won't come up at a later time.

When a buyer knows they want to buy and buy again fairly soon they need to target the homes in order.Bank loopholes which cannot be questioned; Buying smaller home first, then buying bigger home (Sqft/GLA) we review it as growing family, need space for office, dogs etc..

HiI’m confused about the Short term rental loophole.

(And no, there is no "acquisition debt" loophole, since the property was free and clear)Step 3. $80k is used for business purposes.