This isn't a doctrinal issue, as I'm sure you'll agree.
Doctrinal as defined as . . . consequencing ones salvation, then no. But I'm confused on your definitions. If I understand your correctly, you are making a distiction of doctrinal and intrepetive on how clear it is. Things that are obvious = doctrine. Things less obvious = intrepretive. I'm not sure that is helpful for several reasons.
Things we consider clear weren't always clear in the Christian Church.
If God commanded something, even if it isn't clearly commanded, it is still sin not to obey it.
I think Christian liberty pertains to things that are not wrong in themselves but may be wrong by means of conscience, lack of faith, or falling into sin. I think simply disagreeing over what is inherently wrong is a matter of realism and peace among ourselves, since we can't agree. Ideally, we could all agree on those things.
Pauls examples were meat offered to idols and Jewish celebrations and sabbaths. Meat was not inherently wrong because, hey, there is no real other god to offer them to. The celebrations were not mandatory because they were a shadow of the reality that is faith in Christ. They had to have meetings about this to sort that out (acts 15). But Paul would not say (in my intrepretive opinion

) that greed, or lust, or stealing, or pride, or any such thing is permitted because we have liberty, they are inherently wrong. In my opinion, alchohol, narnia, video games, etc are not inherently wrong or condemed agaist in scripture. Murder, rape, injustice are, and so would not having children, IF (huge if) it was supported as inherently wrong in scripture.
BTW, for revealing biases on these matters, I am 27 and have two kids.