Will they work? Not sure. Is it okay? Definitely. I'm pretty sure any sort of protection, like knee pads or gloves, are completely legal. When you're wearing garb, though, I'm pretty sure it has to be either hidden under the garb, or changed to BE the garb. What I was going to do (because I have similar problems) was get athletic tape and just use that for every practice, since it's just twice a week anyways. If you're not being hounded on for garb yet, you're completely fine with bringing protection. Once you do...meh, cross the bridge as you get to it :P