if heat is the reason you are keeping the light so far away try putting a small squirrel cage fan in between the light and the plants to help disipate the heat or you could get a piece of window glass and place it close to the tops of your plants then putyour light above the glass get a fan blowing on the glass at high speed the glass will protect your plants from the wind and allow you to keep your light cooler and closer to your plants the piece of glass should fit snug in the top of your box

starting over might not be a bad idea i had to do it twice it sucks but maybe you could cut some clones from those to start your next grow ?

whatever you do good luck-Bomb