Hello BP community,I'm interested to learn what most investors do with the portion of rental income commonly set aside for cap ex, repair, and vacancy costs.

Properties, for novices, which look good on paper and have good cash flow usually come with C to D+ areas, risky tenants, and a lot of cap ex that you can't see on the internet (basements, roofs, water issues, outdated mechanicals).You are turning a terrible loss into a springboard which is great, but you are trying to move too quickly it sounds like.

I've been doing land and cabins and I partnered with ex brother in law to get our gc license last year.

Just call him, all that you want to know in the questions above he can answer for you.He is incredibly nice, but nonsense, he is ex military (navy if I remember correctly).He is not a hard sell kind of guy, in his estimation you either want to invest or you don't so he is not going to chase or pester you.  

Most new investors have a lot more cap ex risk exposure than they realize.

No vacancy, tenant turnover, PM, typically lower maintenance and cap ex costs, less book keeping.  

My ex wife lives in the house, let her pay the mortgage1.

What if large cap ex items pop up?

I do not agree with the OP on reasons for cash flow being unpredictable as maintenance, cap ex, vacancy, property tax, insurance, etc should be thoroughly evaluated and covered in the underwriting. 

You can buy an almost new or brand new single family home here in Arizona for $250-300k, combine taxes and insurance of under $2k per year, rent for $1500-1800, will break even on cash flow with 25-30% down because there is no maintenance or cap ex since it's new (you will have these eventually but rents will increase by the time that happens).