A question about pickup covers (and something else)

I'm having a custom bass built and Iwant to put ken smith pickups in the bass but I don't want everyone to know they are ken smith pickups so I want to put pickup covers over them. I was just wondering do pickup covers affect the sound of pickups??? Also I wanted to put a smith pream in but I want a diffrent color of hardware, whick he dosent sell (never seen anything but black knobs and switches on smiths) do you guys know where I could get diffrent color switches and knobs? Thanks!!!

 

I met to say custom matching wooden pickup covers over the pickups. But in general, do pickup covers affect the sound of a pickup?