I doubt that you will find anyone that will rent a groover out. They are expensive and can be forgotten at camp or come back not clean. Most people won't want to deal with that hassle. If I were you I would just pick up a 5 gallon bucket with a gamma lid or get an old 20mm Ammo Can from an army navy surplus store. Either is cheap and legal on MFS. Good Luck.
When you spend your life in the rain, you learn to walk between the drops.