This video has some interesting views on how it could be feasible: https://aussie.zone/post/5422070

By 'refurbishing' the existing sleepers, I hope they mean stripping it back to a set of wheels then re-building everything above, because there is nothing in the current sleeper carriages worth salvaging... the whole thing squeaks and groans and makes for the worst might sleep imaginable (unless you are dog tired). They are well past their used by date