Do they make paint stirrers for 5 gallon buckets?

I only see short ones that attach to a drill, and are made to mix gallon
cans of paint. I have several 5 gallon buckets of a roofing sealer that
have been sitting for years and settled. It's a tar-like material, and
rather thick. Stirring by hand seems near impossible. I just need a long
enough stirrer to put in my drill. I have a powerful industrial plug in
drill that should handle the job, if I can find an appropriate stirrer.