You may feel that I misunderstood the question as well, so I'll restate my reply.
I can't imagine how severe the downside of an alternative would have to be before I'd be willing to have my Constitutional rights, the proper balance of power between me and the state, abridged to avoid it.
OTOH, I also have no problem with leaving drugs illegal and simply repealing the laws and court decisions that have granted government new powers to fight it, or kiddie porn, or terrorism, or whatever the bogeyman du jour is. I have no problem with them fighting it to whatever extent they can under the traditional understanding of the BOR and without spending much of my money on it.
One, keep things as is.
Two, legalize drugs. (Details may vary depending on which drug, etc.)
Three, make policy changes while keeping the production and distribution of drugs illegal. This would include changing punishment, abolishing asset seizures, etc.
My main point is that whatever is done the costs must be weighed against the benefits of nay given policy. I'm not sure a strict libertarian approach is honest in doing that.