Get another ferment bucket. If the bottling bucket leaks a little while bottling, it's going to leak for the whole fermentation period. I wouldn't trust it even if you think you have the leak stopped. I have broken off the threads of a bottling bucket valve trying to tighten it to stop a leak, so I would use caution. Another thought, the valve/spigot would get pretty nasty sitting in the trub/yeast that settles at the bottom. It would probably be hard to clean and worst case scenario, could increase chance of infection. I would get a 7.8 gallon bucket,.