It's very cheap but you need find qualified and high credible virtual assistants that could get the job done.

Would I just continue to buy one house at a time or would it be better to try to scale up (larger package of sfh or small multis) I work a steady job and my strategy right now is buy and hold.

But they also seem like quality tenants and they’re going to be here 4 years because of their job.

Most people don’t want to lose their job.

From my day job I do know a couple successful people in commercial real estate so I will be talking over with them too for their input.  

I understand that while my job is stable and I make "decent" money as a single mom, what am I truly working for?

I have a good 8-5 type job that pays me well.

Luckily I landed a small job to offset some costs and I think it's very doable. 

Given the size of the property you may consider providing discounted rent to a resident to handle some of the on-site management tasks that @Omar Khan and @Ivan Barratt mentioned.

Great job!