You will want to have demonstrated income from the business that you file on a schedule C if you are a sole proprietor.  

They only mentioned that I had to form a LLC in order to apply for the loan; sole proprietor was not an option.

This works AND starts the clock that some states need to see 2 yrs of broker work to award full "individual proprietor license."  

Contrasting that to agents I have worked with that are sole proprietors, in both sales and purchases, communication is slower and deadlines are close to being missed. 

Based on my research LLP/LLCs offer similar* protection from liability, however LLCs can choose to be taxed as a partnership, proprietor, or corporation; whereas LLPs each partner reports profits on personal tax return.

As a sole proprietor all your personal assets are at risk if you get sued by a tenant or anyone else.

Keep in mind, depending on how you want your LLC taxed, sole proprietor, scorp or partnership, you could have an additional tax return that needs to be prepared for each LLC, which can be costly. 

And if you're a sole proprietor DBA they'll let you link the accounts so you can transfer money bank and forth as needed.Would not recommend online only. 

I already have a solo 401k that I set up years ago as a sole proprietor with an EIN number.  

@Kyle SpearinIf you haven't set up a business through your state corporation commission, you are a sole proprietor.