As far as I know, there isn't a "pure" way of achieve thing, though you have a few options of varying involvement:
Chrome/Edge + modified Qlik virtual proxy + local Windows accounts + browser extension
Something you could try would be set up local user accounts on the Central node, one for each screen (which I'm assuming are operated by separate Windows boxes). They would all get an Analyzer license. Then you could create or modify a Qlik virtual proxy to have a long Inactivity Timeout duration. For each screen, make sure that Chrome or Edge is installed, then add a browser extension that will automatically refresh the page at a certain interval. You could use something like this (just the first one I found when searching, I have not tested it and do not testify to its functionality or safety). When you put all of that together, you'd be able to have one or more dashboards up on each screen that stay refreshed and "awake" while not producing any extra files, unless you wanted to write a PowerShell script or something to automate the daily set-up.
Chrome/Edge + modified Qlik virtual proxy + local Windows accounts + Python script
This would be basically the same as the previous option except that you could write a Python script that uses something like Selenium to automatically refresh the dashboard webpage at a certain interval to keep it from timing out. This option would involve at least one file to keep track of but could be good if you don't want to have to trust a third party browser extension to have access to your Qlik environment or if your organization's policies disallow extensions entirely.
Mashup + modified Qlik virtual proxy + local Windows accounts
This would be the option you linked to, where you would embed the dashboard as an iFrame element in a custom webpage. This would really only be one file that you'd have to keep track of but it would not be a file that you'd have to maintain at all unless the dashboard URL changed (but I guess that would affect each of these options anyways).
Qlik nPrinting HTML report + PowerShell script
This option would involve the most extra files and maintenance, but would allow you to not create new local accounts or use up extra licenses. You would, of course, need to have the Qlik nPrinting product for this to work. The gist is that you would create an HTML nPrinting report that would basically just include the dashboard itself (or the visualizations therein inserted separately). It would also include some very basic JavaScript to automatically reload the page at a certain interval. The report would be scheduled to run at a regular interval, perhaps every few minutes, getting dropped into a Windows network folder. From there, you could have a PowerShell script that is set to watch for new files in that folder, unzip the new ZIP file when it appears, rename the HTML file, and then delete the old one. Then in your browser, you would simply have that HTML file open and when it refreshes automatically, the newly-dropped HTML would be what is now shown.
Screenshare?
I wouldn't even know where to start with this option...just a brainstorm!
