I am currently writing my business plan the deadline for it is March 10th, 2024 then I will hire someone from fiver who is smarter then me at writing and they will take what I wrote and make it look better and presentable.

@Jake CyeedA Solo 401(k) such as @Joe Homs has is a different form of retirement plan, designed for people who are self-employed and have no full-time employees in any business they control.   

Turn it into a business rather than thinking about 1 single transaction 

If you determine it's a viable business model in your area, develop a Plan B; you likely won't need it, but it's still important to have.

I have a few questions: 1- Is this a legitimate way to set up a business?

I currently own and operate two STRs in Minnesota (1 in the Brainerd Lakes Area and one in Duluth) and think owning a vacation rental in a market where the winter and spring are the busy seasons would be nice to offset my current slow seasons being in northern Minnesota. 

A business that I currently own may have had some rights to the property.

You're at the level where you shouldn't hire a property manager and instead build an in house property management team to take the busy work off your hands.

Go through their numbers, drive by a few of their properties/rehabs, and start getting a feel for this business.

As a newbie, my first question is around how to start out.What is the best type of business for Real Estate Investing to get the best tax break?