I like clear pickguards. They visually break up the face of the guitar while still letting you see through to the finish. The effect is similar to the way body panels on cars are contoured.
A
white pickguard would also look nice for that red. Of course, a white pickguard would make it very Strat looking. If you want to be a little daring, a really deep purple (almost black) would be sweet.
Ha ha, I said "deep purple."
I've always thought that red guitar +
black pickguard looks cheap but that might be because my first guitar had that color combo and it was a complete POS.
I'd be careful with a pearloid pickguard if the grain on the wood is going to visible. The textures might clash and the guitar look garish.
All IMO, of course. You should just do whatever you want. And post pics.