Toilet lid covers for WaterRidge High Efficiency toilet from Costco

[Kuuipo]

I cannot locate any store that carries a toilet seat cover for the WaterRidge High Efficiency Tiolet with dual flush from Costco. The enlongated ones aren't wide enough at the bottom to stretch around the "wings" at the base of the inside of the lid.....
Anyone else have trouble finding these? Or maybe you aren't supposed to use toilet seat covers on these slow closing lids??
Thanks