Sincere apologies I should have updated the thread post Essen too busy with my new shiny games.
The smallest sleeves available are by Swan and measure 38mm x 60mm.
They are both too long and too wide. I have cut a few of them down and they work in a fashion if you can live with the width problem.
No ideal solution I am afraid!
I see no one tends to think sideways.
FFG Mini Euro with trimming fits the small cards oriented longways against the sleeve's width.