Creating Infinite White Background For Full Body Shots

Hi guys,

I've been filming some videos on an infinite white background but I'm having issues with getting the lighting consistent. We're using white paper as a background and styrene plastic for the flooring because there is carpet underneath and circumstances won't let us replace it. We're shooting full body shots and I'm having trouble getting the lighting strong enough and consistent without overexposing the person. It either won't be bright enough or too bright if I try and compensate. Does anyone have any ideas of how I can fix this? 

Cheers