I know this is delayed, but I just got a couple "Duramask" brand flymasks for my girls and so far they've been great.
They've worn them about 15hrs/day for the last week and no rubs yet, even on my foster who has never worn a flymask before this. The girls also haven't been able to remove them yet so that's good too!
They're made out of the same type of sturdy material that Kensingtons are made of as well!
I paid $15 per mask but it looks like you can get them cheaper on Amazon.
Just thought I'd let you know, in case you ever want another option. :)