Avoid mixing relationships and business.

They were “earning my business” by doing an hour or two of extra work.

My business partner has two STRs adjacent to ours that has several 1-bed units that rent very well during the week. 

Before becoming a designer, I was a systems engineer and business analyst (MIS degree), so my process is deeply rooted in formulas to keep the right elements at the forefront.

As you progress your bookkeeping business, you'll likely want to learn how to export statements from a variety of property management platforms, as investor books are housed in bank accounts, spreadsheets, and a variety of property management and accounting software!

My first thought was to check BP because...you know...BP.Has anyone conducted business with or heard of: https://zoodealio.com?

You can use a bank statement program, (1 year 1099) and depending on your schedule E or how you show your passive income or Schedule C depending on business tenure you can use just one.  

New to this whole business.

Numbers and relationships drive this business.

That is a very dishonest way to operate your business, and will get you a bad reputation and lose you money.