A bit different than what you were intending perhaps, but I would point to:

Louis E. Keefer. Italian Prisoners of War in America, 1942-1946: Captives or Allies?. Praeger, 1992.

Bob Moore & Kent Fedorowich. The British Empire and Its Italian Prisoners of War, 1940-47. Palgrave Macmillan, 2012.

Both of these look at a critical aspect of Italy's changing sides, namely what to do with the Italian POWs held by the allied powers, and provides some insight into how the Americans and British tried to balance the new, nominal status as 'Allies' with the desire to utilize the (former) POWs as a source of grunt labor, as well as how that change in status allowed them to use the Italians in roles otherwise prohibited by the Geneva Convention due to its direct impact on war work.