We recently had two applicants go through the screening process for a rental unit of ours.

Since it's ideal to approve a rental applicant with income 3 times the rent, I wonder if combined income of multiple applicants over 18 who will be living in the unit qualifies this requirement? 

Looking for suggestions on management software/apps and rent payment options.

@David WilliamsThe issue with bookkeeping is that it is a service that can take a long time(especially if you have different expenses every month) and it is a service that is often not appreciated by the general public.Another issue is that getting a bad bookkeeper will cost more because someone else will need to fix it.You may want to see if you can do the books yourself with the help of a CPA reviewing them on a quarterly basis.There are features within most accounting software's that allow the bank account to be linked to the accounting software.

If the tenant does not qualify on their own and you don't want the entanglement of a co-signor then move to the next applicant. 

Listings, screenings, showings, applications, leases, managing tenant issues... 

There is potential it could change in the future with the city plan, I could try to get a legal non-conforming letter from the city if its applicable and/or try to rezone it but what if I'm not approved?

I would go a step further and actually call the current offerings and get details - security deposits, who pays utilities, application fees, what's their process for viewing and applying, etc. 

We also are able to fill many of our vacancies before we put the house on the market because of the backlog of applicants.

I'm looking a recommendation for an app/software/etc. to generate a rehab scope of work (based on physical or video walk thru, ideally with ability to ballpark cost based market norms or user inputs).