xrandr settings make one screen extend beyond the display

I've been mucking around with this for ages now and have hit a wall. I can't find exactly what I'm looking for anywhere through searching either.

My setup is two 4K monitors. The one on the left is the internal laptop monitor that I want to increase the size of by about 10%. The one on the right is a huge 4K that can stay 1x1.

The randr stanza

xrandr --output eDP-1 --pos 0x0 --mode 3840x2160 --scale 0.9x0.9 --primary --output DP-1-2 --pos 3840x0 --mode 3840x2160

gets the screens about the right resolution, but the menu on the bottom drops off the visible area of the screen.

I've tried setting --fbmm 8064x4536 and --fbmm 7640x4320 but they doesn't do it for me either.

I've got to be close, anyone know what the stanza should be?

It seems the missing piece is the restarting of plasma after changing the screen if the menu doesn't appear where it should.

 →  kquitapp5 plasmashell && kstart5 plasmashell

Still playing with the fbmm settings, but its working pretty well at the moment.