You won't be too happy with the clear lenses, if they make them. Remove the fixture and look on the back to see who made them. The ones I have are made by Progressive Dynamics (yes the same people who make the super reliable converters). I'll bet there are clear lenses available for you fixtures.
As I noted, you won't be happy. The frosted lenses help to spread and redirect the light, as they did with the incandescent. With the clear lens, an incandescent will still spread the light, however LED's, especially flat panel ones, are very directional.
I used flat panel lights from M4Products, which I installed after the Goldstar flat panel ones I bought that plug directly into the sockets, began to fail. Turns out they don't have any heat sink and were cooking themselves to death. The M4 has a aluminum heat sink and the circuity is isolated from the LEDs by an air gap, so it runs cooler.
Charles