The old AMD "Catalyst Control Center" (now "Radeon Additional Settings") has a feature where it forces the Windows taskbar onto a single monitor in an Eyefinity setup. Unfortunately it requires "Radeon Additional Settings" to be run in order for this preference to be instigated. I'd like to see similar functionality in DisplayFusion where it would be properly supported.
You should be able to do this with the DisplayFusion Monitor Splitting. After enabling splitting, you'll have a taskbar on each monitor. You can then disable the ones you don't want by right-clicking the taskbar and navigating to Multi-Monitor Taskbar > Position > Disabled.
Hope that helps!
The DisplayFusion taskbar isn't identical functionally or visually to the Windows 10 one. I'd prefer to use the Win10 version.