With the 4.3 release, you can set custom resolutions for screens that use the AirPlay workaround in 10.13.4+. Look for a new icon with a menu in the top bar. More here:
https://displaylink.org/forum/showth...6656#post86656
Please read
https://support.displaylink.com/foru...ve-10-14-early to decide if this is a good moment for you to upgrade to Mojave.
Cheers,
Michal