Workaround that I use, I have 3 custom slides, one is assigned a black background theme, blank. One is a blank slide using the "default" theme so that it keeps the service background image in place, and the last is I forget how it's set, but all are blank content, and serve different functions. The "blank" theme I have created is black text on a black background, so I can also use it for stageview only stuff..