At least if I want to outsource the process , I can invest indirectly to mortgage note fund.

Property management company - You outsource it to a property management company and your approach is more hands off3. 

When to outsource it?

Others may outsource services to private companies, such as maintenance or administrative tasks, to leverage specialized expertise or cost efficiencies.

You need a firm budget (you would be outsourcing too much of this to someone else.)If you want to house hack, but a multi and do it, but make sure the numbers look good for when you leave because in most markets they won't look great while you are there unless you can get 3 or 4 units.

A lot of manpower is lost.As we approach our busy section 8 season (for us April - July) I am looking for better ways (more affordable and efficient options to the investors bottom line) to plan for and execute the workload which may include hiring someone that has section 8 experience to handle our CHA inspections(and associated maintenance work) or a company that we can outsource when the weeks get slammed with inspections. 

Hiring one company to do the whole deal and outsourcing parts of the deal (using contractors and agents) is completely different.

Might come out green overall but it’ll be close.bonus: if you’re willing and capable to do an excellent t STR, which I would budget a good $40k-$50k on the furnishing/design/decor (more if you are outsourcing it all) AND are putting down 20%+, you’ll be able to have a very positive cash flow asset.

I'm looking for advice on how to best outsource bookkeeping for a rental portfolio of 15 - 20  SFR and small MFH units. 

There are several options for outsourcing skip tracing.