Not 100% happy as they are not as 13-year old boy -proof as I'd hoped.. but here's what I came up with..
In Libre Office I designed a simple layout - these were printed, laminated and stuck to thick card. I then stuck four transparent card holders onto the new cockpits, to hold the pilot and three turn cards.
These are definitely smaller than the originals and they do work. (although they don't help me to win as both Richtofen brothers got shot down last night!)
They don't allow for easily displaying '+1' damage cards however, and are a little prone to knocking. I shall consider them as Mk1.