I have a weird kind of respect for David Friedman mainly because I think he's among the less nutty of the Ancap crowd and one of the only Ancaps with a decent level of self-awareness, he also doesn't claim his ideas would work perfectly and more importantly isn't an Austrian.

There's also this video where he basically spells out some major issues with deontological libertarianism and basically admits that the theory falls completely flat in some areas and that there are no solutions to arguments he brings up, it's really worth a watch.