Just about any USB extension cable will cause enough of a voltage drop to cause problems charging. This is especially so with the iPad 3 - but the iPad 2 will also suffer.
I have not seen any USB extension cables myself that have heavier gauge power wires (that would reduce the power loss) - not to say they don't exist, but I have yet to see one myself.
If you're not against the power brick being closer - you can get a PS3 slim power cord on Amazon for 3.75 with free shipping on prime. Simply pull the prongs off your iPad charger - and you'll see the inside will accomodate the PS3 power cord. That is cheap - and you won't have that power-loss issue this route.
Just received another of these last week, as a replacement for a lost charger. These are the real McCoy, at least from primary vendor.