UV mapping of a rounded box

Hello, community,
It seems tricky to correctly UV map a rounded(filleted) box in Rhino.
Any ideas?

Hello- that should look better with box mapping, in this case -


Hello Pascal,
I have tried all the possible techniques in Rhino (box mapping among them, with and without cap) but it improves slightly.(((
I think UV mapping is Rhino’s “Achilles Heel”.
Is any tool in Grasshopper for UV mapping?
Thank You.