Complex modification with exception rule for specific key-press combination

[Vilscon]

I've remapped my Mac CMD-key to the Option and my Option key to the CMD-key when the frontmost-application is Windows Remote Desktop (because there is no other way to remap CMD to CTRL, instead of the Windows Key). However, I use Spotlight all the time, also to switch between applications.

I want to create an exception to the CMD→Option key for when the CMD key is pressed simultaneously with the space-bar. Is such thing possible?

The complex modification script would look a bit like

frontmost-application: Microsoft.rdp.osx,
from: left-command
to: left-option
exception: spacebar-pressed

For the record: spacebar is always pressed (in my case at least) after pressing the left-command key.