I use the old Camco corkscrew type, like you'd put a pet on, and happy with those but, sand is a different story. How bout a couple of empty 5 gal buckets and fill them with water? Full would be roughly 40 lbs. Or if you carry a couple jerry cans as I do, tie off to them maybe?
2016 Flagstaff 27VRL Emerald
2020 Silverado 2500HD CC 4X4 6.6L gas 3.73