Very sorry.
I tested the level in parts, I thought, but apparently I forgot about the flag at the bottom left. It looks possible to get, which is probably why I didn't consider it, but the portal directly above it makes it impossible to get. Or maybe I forgot to set the required flags to 6.
I tried several things just now, even cable-caring the pipe under the other portal, but it does not seem possible.
Fortunately I am testing my next levelpack a bit more.