I looked around, but I didn't find an option to be able to do continuous preview images for adjusting my rig in EKOS. I just could do single images or sequence (but I don't want to store the images). Is there something I overlooked ?
For this item what I usually do is to use an option that is located in the Focus module. There is a button called "Framing" that works exactly like what you are looking for. In fact, you can even set this Framing Image to display full screen which is quite helpful for manual focusing but would also be quite useful for your purposes.