Hee hee Backwoodsman! Quite so. Round here (deepest Norfolk) many Eastern Europeans used to come and work in the fields, and farmers would provide caravan accommodation for them. They always spoke well of these folks' 'work ethic'. I used to ask why the farmers didn't employ local youngsters, and the answer was always, "They won't come. And even if they do, they skive off at every opportunity!"
I don't think this new idea could be termed 'slave labour' because the prisoners would be paid appropriately. (In many prisons I visited, paid work was available on site, stitching mail bags, packing tea bags, and anything NOT involving sharp instruments!) But they still managed to do naughty/dangerous things behind the officers' backs.
Good idea, but fraught with snags and drawbacks I think.