> I would argue indentured servitude is a valid way to go, but it makes people uncomfortable because they see it as slavery

I don't see any discomfort presently, even though the constitution exempts prisoners from protection against slavery.The Thirteenth Amendment, Section 1: "Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction."[1]

1. Stolen from https://news.ycombinator.com/item?id=2037139