Have four rentals and one flip under our belt, but I'm afraid we're doing the wrong way as a sole proprietor.

Can I do this as a sole proprietor, and structure their investments as "loans" with repayment terms that depend on ROI? 

All the things that are real world but not attractive or marketable aspects.The proprietors of this site have a business model that benefits from engaging viewers to remain on pages and view advertisers' messages. 

From my research, it seems that an LLC is the way to go for small operators who'd otherwise go with "sole proprietor," and it's the way I'm headed.

What kind of protection is it for a sole proprietor like Joe Fish dba RE Investor?

One property makes it hard to justify a home office.Again with a single memeber LLC only holding a rental property it is a disregarded entity and therefore filing Schedule E on the proprietor's 1040.Continuing education expenses beyond typical amounts are not an ordinary and necessary expenses.

We budget for capital expenses and operating costs.How you take cash out of your real estate investment business depends on the type of business entity you have and your goals.Here are some examples from our experience:Sole Proprietor: The only money that goes into our personal pocket is the money we take out as an owner's draw.

@Alice Jackson  If his MHIC license is under a corporation it will be easier than if he holds his MHIC license under his name as a sole proprietor .

Assuming you are planning to operate the multifamily as a rental, there are no tax benefits available to a pass-through entity (LLC or partnership) that you wouldn't have anyway as a sole proprietor.  

Furthermore, if your rental activity results in a loss for the year, you can use the net passive loss allowance to offset up to $25K in ordinary income on your 1040.Most of these tax advantages would be lost if your rental property is held in a C-corp.You still have all these tax advantages whether you own the rental property in your own name or in the name of some passthrough entity such as an LLC or an S-corp. .As far as I can tell, there are no tax benefits available to a rental property activity owned by a passthrough business entity that you don't enjoy as a sole proprietor.