Some of the listings on AirBNB, VRBO or similar could be using the 30 night minimum to be considered a MTR allowing you to bypass some of the STR regulations.

I've noticed a pattern in my local market: there are numerous sellers who are motivated to sell and are willing to go lower than what they paid for the property a couple of years ago.

I've posted on these subject numerous times lately but building codes across the country continue to evolve making the construction execution costlier and costlier.

You should have some good economic reason for converting it.There is no court case or regulations specifically prohibiting this, nor telling taxpayers they can do this, from my experience, but again, you asking this question and it feeling a little "too good to be true" is usually a sign the IRS may scrutinize something like this, especially if done repeatedly. 

Every coastal town has a different set of rules and regulations regarding short-term rentals, so be sure to understand what the regulations are before you buy a place or you may end up being stuck with a property you can't use the way that you intend. 

However, that has come with a few challenges recently as many destination markets have clamped down on Airbnb regulations and many have also seen a dramatic increase in supply of listed Airbnbs, particularly over the last few years when the Travel sector boomed coming out of the Pandemic.

Just don't plan on student housing as it is highly regulated.

G2 promoted a strategy focused on drilling numerous shallow wells at a lower cost, rather than investing heavily in a few expensive deep wells.

Quote from @Grant Shipman: Hey BiggerPockets Community,If you’re raising capital for real estate syndications, you need to be aware of SEC regulations—because one wrong move could put you in serious legal trouble.Many new syndicators think they can just start pooling money from investors without following the proper rules.

Less burdensome regulations than STRs. for #3, I would not discount the lease if possible.