How to Configure Multiple Displays with Different Dpi Settings Using Xfce >= 4.14?

XFCE 4.14 promises HiDPI support. I'd like to use different DPI settings on my laptop screen and on the external monitor, but I can't find any new features improving this particular situation. So what does "HiDPI support" mean then? Is this for Wayland + XFCE only?

What I did before XFCE 4.14

This seems to work for < 4.14 and for >= 4.14 the same way:

Custom DPI settings in Appearance -> Fonts allows changing scaling of windows for both monitors at the same time:

This works only for one screen unfortunately. The best I could come up with is adding this script as shortcut to toggle between different settings:

if [ $(xfconf-query -c xsettings -p /Xft/DPI) = 152 ]
then
    xfconf-query -c xsettings -p /Xft/DPI -s 96
else
    xfconf-query -c xsettings -p /Xft/DPI -s 152
fi

Many applications (Firefox, Thunderbird, ...) need to be restarted after changing this setting unfortunately.

What is new but doesn't help

I think the Window scaling option is new (but I'm not sure), but it offers only 1x or 2x scaling for both screens at the same time. This is not helping in my situation.