The Ancaps need to address any relationship between those who own their business and those who work for any said business. An Ancap can run a very successful business loaded with child labor. It would be a fact that that Ancap would become extraordinarily wealthy via an unjust relation yet it would still classify as anarcho-capitalism.
For anarcho-capitalism to work in alignment with the principles of non-necessary exploitation and coercion(voluntaryism) there would need to be a baseline minimum income. The only way to do that as far as I can tell is in a new distribution of how currency is created. Right now currency is created by debt via force and given first to the Central Banks who then have first dibs on all kinds of resources. Of course, new neo-homesteading would solve this issue, too, but that solution doesn't address scale--how is NYC's population to become farmers again?
What I'm saying is that there have to be mechanisms within Ancap philosophy which prevent this economic system from turning into neo-feudalism. If this issue isn't addressed then Ancap. would be deluding itself and dismissing the foundational (and spiritual) concern of voluntaryism. I can see Ancap working if all those involved are at the 'buddha and christ stage of development' but problematic with those still at 'mafia stages of development'...
Here are a few links that distill the issues.
http://andrewmarkmusic.com/?p=1714
http://andrewmarkmusic.com/?p=1732
Why should children be forbidden to work? If child labor were not a black market, why do you think child labor would not find a market price equilibrium? The more prosperous a society due to free markets and advanced mechanized productivity, the less need there is for the Dickensian hardscrabble life.
Why do you assert a need for a baseline minimum income? This is merely a statement, not a rational argument. Without government parasitism, the wealth productivity realized by the worker is far higher and his cost of living far lower. You are correct in observing that the government monopoly money system is broken, but that is hardly a fault of free market anarcho-capitalist principles in action.
Feudalism is antithetical to markets. There is no relation between them except the most superficial and fraudulent application of terms like "property."