In the rural US, any district outside an urban area is NOT a 'bare majority republican district'; they're all large majority republican districts. Rural America is devoutly republican, outside recently formed border districts (formed since 1980) that are largely immigrant.

Most gerrymandering doesn't bias rural districts; it biases suburban districts that are marginal majorities (usu republican) only after redrawing the lines. Any automatic line redrawing algorithm will defeat this, since it takes a lot of perverse effort to draw boundaries that are sufficiently biased to serve Machiavellian pols.