Hm. Okay, so the endcaps are here and I see the problem.
Nuke 3in1 endcaps are screwfit not push fit like Hope etc. The larger axle sizes have flats like overlock nuts for installation. I was hoping the QR models were likewise but they have an Allen fitting in the skewer hole instead, which would obviously be lost on drilling.
The next obvious idea I suppose is filing or cutting flats but it looks like if I do so the toothed portion that grips the dropout will probably fall off. It’s only a thin metal band round the plastic cap on these. Any ideas? If I was using 135×10 RWS skewers is the serrated surface on the endcap even needed?