if its over eight foot tall then the bottom 4 feet is gunna suck if all you got is a 1,000 hung horizontally over the top of the plant...growing plants that tall you should grow the lights in vertical tubes so they hit every angle of the plant, however, if you grow a huge bushy plant topped and pruined well then a 1,000 horizontally hung above the plant would do just fine....
you need to provide more numbers to really get an accurate answer here...really pictures...its possible for 1x 1,000W vertical to not be enough for even one plant , its even possible for 3,000W to not be enough it all depends how its setup (angles, distance, and number of lights etc) and the plant..
lastly i just want to say...sounds like you neeed to tie your shit down