So for a while I've been thinking about a way to weigh down my lights when Im shooting on location (specifically on the beach) since I dont ever bring an assistant and there's no guarantee someone is going to be coming with the model.
I thought about buying actual sand bags but didn't I like to travel light and fast (camera and lighting bag only) and didn't want to literally be weighed down by adding a whole bunch of heavy sandbags to carry around.
The solution I came up with was a 5 gallon bucket, trunk tie down, and a utility shovel.
I took apart one of my light stands and attached the trunk tie down to the light stand. When I get to the beach I carry the bucket and shovel down along with my other gear then fill the bucket with sand, attached the trunk tie down and tighten the strap.
Once the sand is added to the bucket I get about 50lbs worth of weight attached directly to the stand.
The added bonus to the trunk tie down is it has an additional metal loop that comes in pretty handy for hanging my lighting bag from the stand which keeps it out of the sand and adds about another 15lbs of weight to the stand.
For extra windy days you can buy a second bucket and trunk tie down for $8 and put it on the other side of the light stand.
Here's a picture of the setup. Hope this helps someone out or gives you some ideas.