Thanks all for all the ideas.
Usually people put the skis together,
stuck with Voile straps or similar.
Stuck to the frame,
with a good part hanging at the back to avoid banging the knees on bindings.
My set up is shorter and slimmer than skis,
with no bulge from bindings,
just minimal inserts.
I want to leave the Carradice at the back to stick the rucksack on.
The boards have to come forward
on each side of top tube,
with the edges inward to avoid injuries.
It s more balanced,
and the Carradice is interfering with the usual rear placement anyway.
I m not desperate,
I just have the skis on my back tied to the emptied rucksak.
All the stuff goes into the Carradice.
15 k max cycling.