most rides will either have creeks or water troughs to drink from, depends on area, I wouldnt count on troughs if there are natural places to drink. You really need to work on your horses water issues. A horse that wont drink from a creak is a huge liability on an endurance ride. The bucket is handy, can be tied to saddle and holds a big sponge, you can scoop water to throw on your horse, get water if other horses are crowding the source, or if he can't get to it. Same with the sponge, use to wipe on and off water,
My cantle bag contains two rolls of vet rap, stuffed behind the water bottles, a few zip ties, a wad of parachute cord, Inside a ziplock bag is a small pill bottle containing, an asortment of pills, heartburn, tylenol, motin sickness, chapstick individually wrapped womens panty liners, a baby diaper, couple handy wipes, and a single paper towel. Leatherman multi tool with a razor sharp blade, a packable raincoat, some mechanics gloves and a polar fleece, water proof matches, lighter.