Yes, I used Bel Edwards's victory map from 2015. He lost the white vote to David Vitter 60-40%, and that is about how it would go here. So Louisiana would be one state. For South Carolina, I used Jimmy Carter's victory map from 1976. If you look closely, Greenville County votes Republican (and is the most populous county in the state), along with Lexington and Aiken Counties; Richland County gives ~50ish percent of its vote to Rutherford; and Charleston County is carried by him with a plurality. I'm not sure how the white vote went in 1976, but Carter won South Carolina by 13 points that year.
Given how demographics have changed since then, it's possible that Leach wins the white vote (though that is ambiguous too since most of the state's rural counties go Democratic here). There are several other states that I think are in doubt as well, or should be considered. For Georgia, I used Zell Miller's map from 2000, and on US Election Atlas, it was determined that he won the white vote that year, the last time a Democrat has done so. The maps for Tennessee, North Carolina, and Arkansas are from 1964, and Johnson almost certainly won the white vote in those states.
Florida is ambiguous; I used Lawton Chiles's map from 1990, and he won by 13 points that year, carrying most of Florida's counties bar Duval County, Marion County, Lake County, Brevard County, Collier County, Sarasota County, Lee County, Charlotte County, Clay County, Martin County, Escambia County, Okaloosa County, and several others in the Northeast and along the Gulf Coast. Bill Nelson won by 12 points in 2012 in his most recent victory, but lost whites to Connie Mack IV 52-47%. So, it's possible that Leach wins Florida whites as well, especially given the counties that he wins or breaks 40% in. Oklahoma would be a definite Democratic victory among whites, given the very strong percentages earned in the rural counties, and the carriage of Oklahoma and Canadian Counties.
So, of these run of states, the ones that I can think of where Leach wins or probably wins whites are Mississippi, Alabama, Louisiana, and (possibly), South Carolina and Florida. But as I asked you above, what about Virginia and Idaho makes you think that whites would go Republican?