Operate as a sole proprietor for a while.

a sole proprietor LLC can be setup via Legalzoom for a few hundred.

Generally, you are self-employed if any of the following apply to you.You carry on a trade or business as a sole proprietor or an independent contractor.You are a member of a partnership that carries on a trade or business.You are otherwise in business for yourself (including a part-time business)

From an actionable point of view, if you plan on investing as a sole-proprietor, it's better to put all of your time and energy into finding and getting into your first deal, rather than setting up an LLC.

You can still operate as a sole proprietor until you're ready to incorporate.

He also works well over 750 hours, its his full time profession, and owns the business as a sole proprietor. 

You save 85k in cash, and if you negotiate properly with a good landlord and tell him or her your will handle the normal wear and tear items on the home(most Air BnB proprietors who are Superhost keep their units meticulous) if they handle the large maintenance items like roof, HVAC, etc. - Now you have your Air BnB unit but you don't have to come out of pocket a dime. 

- ‘lifestyle’ business – ie simply intended to be run by and to provide an ongoing source of work and income for the proprietors, no clear vision for the long term future?

Or are you asking if you should create an LLC vs just operating as a sole proprietor using a DBA?

An LLC gives you flexibility in how the entity is taxed (corporate, partnership, or sole proprietor).