[X2Go-User] keyboard layout driving me insane

On client side, I have layout set to map caps lock to ctrl. I need this also when using x2go! But it seems hard to achieve. In x2go, I try both 'autodetect keyboard' and 'don't configure keyboard'. I try mate, xfce, lxde. On the server side I would like to try also configure keyboard layout, but I don't find any good way to do it on those window managers.
Unfortunately, neither KDE nor GNOME will work (both client and server are fedora 28).

Sometimes I seem to hit a combination that works, but then when if the connection is terminated and I try again, it's once again not preserving my key remapping. This is driving me nuts! Any recommendations?