If you can do 1080p now thru the switch, why wouldn't you just install VNC on server and client? I've tried all the common clients and prefer UltraVNC for a 1080p laptop connecting to a 4k server. You'll be limited to 720p in prism if you can't go higher than 1080p on the server but that's fine.
To use a dummy plug you'd have to unplug your cable and use the plug instead then switch back for troubleshooting boot issues etc. That's what I do.