also is it ok to run normal brake pads on a carbon wheel in a TT where I rarely touch the brakes?
Tufo makes the good extenders 60 mm long. With those you remove the valve core, screw in the extender, then reinsert the valve core. I wish I had gone that route but I ended up using the Zipp extenders. They work fine I'm just worried if I get a flat the PittStop sealant may not work.
But here is the thing. You spent hundreds, if not thousands on carbon wheels. Spend the 30 bucks on the pads and take the 3 minutes to change them out.