Bankruptcy laws are in the constitution. So if you would welcome debtors prisons you think that part of the constitution should be thrown out? What other parts do you not agree with? Where in the constitution does it make it mandatory to send your child to school?
Article I, Section 8, Clause 4 of the Constitution does not ban the penalty of prison for debtors, but merely grants Congress the authority to standardize bankrupcy laws across states, since the proliferation of such laws among states hampered commerce. I don’t know where you get that this precludes debtor’s prison if the Congress so decides to allow for this through law.
The Constitution does not make it mandatory to go to school, but states most certainly do, and that is the power that is vested in states, as is the conservative position.
Debtor prisons are against the constitution both state & federal, and illegal (although used by the court systems under another name equally as illegal).