Going back to a Federal government of limited and enumerated powers, as envisioned by the Founding Fathers, may be politically difficult. But the theoretical legislative framework is easy.
1- Get rid of the 16th Amendment, and there will be no more Federal income tax. Taxes get apportioned among the states based on population.
2- Go back to the original intent of the Founding Fathers by interpreting Article I, section 8, literally. Congress can regulate commerce among states. Congress has no power to regulate commerce inside a state. The expansion of the regulatory powers came during FDR.
Roll back the power of the Federal government to tax and regulate, and things will start falling into place.
We need a new party that is based around the principles of smaller government. That and emphasis on personal liberty should be the guiding values and focus of such a party.
If/when one arises the GOP will become extinct overnight.