Buckets are the answer. I bring four buckets with lids. As mentioned, they stack easily and I store the tie downs and my extension cord for warmers inside. I set up my canopy on the side of my trailer, and when it's really windy I put two buckets on each corner, and tie the other end down to my trailer. We had a tornado nearby at Topeka once, and the wind took my ez up with four VP cans off to god knows where. I was in the motorhome when the gust hit and I swear it was on two wheels for a second. When I looked outside, my whole pit was just like I left it, but the canopy was just gone. I found two of the cans, but the other two and the ez up were nowhere to be found.
Makes me wonder what the farmer who found the VP and put it in his tractor thought about that funny gas.
Buckets of water is my method as well. As has been stated, nothing will stop it from taking flight if you get a good gust of wind. I can't find a video but I'm sure others remember the other year at road America when the tent off the yosh rig took flight and flung 5 gallon buckets of water across the paddock.
similar thing happened next to us at VIR this year. The wind was whipping the guys RV awning and Ezup and he was no where to be found. We lowered his awning, tables, and put the ezup under his rig. On Saturday he took a good tumble and had some injuries... kind of rough weekend for him.
I tie one side to the enclosed trailer (using tie downs). I use my 3000W interter genny on the windy corner and a cooler or spares box on the less windy remaining corner. I have used tent stakes if the ground is suitable (too soft and you get no bite). Put the stakes in at a 40 degree angle with the top pointing at the wind. If I see high winds or a storm coming the canopy comes down. I believe it also helps a lot if your canopy has a vent at the top. Sure you get a bit of moisture coming in during a hard rain, but the vent significantly cuts down on the propensity for your canopy to become a sail. As other have said, lower the side facing into the wind by a notch helps too. I either lower (and then tighten up the tie downs) or it or take it down overnight depending on the forecast. Eventually lowering it will probably bite me. That Yosh rig canopy was not vented and a lot bigger than my 10x10.
Strap one side to trailer with tie downs. Strap spare trailer tires to other corners with tie downs. Don't use gas cans because gas gets hot and also the cans can fly. Lower canopy down to bike overnight or in a breeze, take down in wind. Leave the Easy Up home if you're going to Willow. And, I learned, never leave it up while you run into town. No one else in pits wants to go chase it for you.
If no fat chicks are available then a spare wheel or full gas can hooked to a tie down strap has always done the trick. Just be sure you're not in gale force winds like that time at Road America when Yosh Suzuki's tent caught a draft and turned the canopy into a trebuchet and launch a water filled pale like 100 yards across the paddock. They caught it on video if its up on Youtube somewhere, it was really something.
I've seen 4" or 6" PVC pipe capped on both ends with an eye bolt in one end to connect to a strap...cut it to whatever length you want and fill with sand...seal the ends with caps.
Having witnessed many windy days down in Long Island, I dubbed EZ-UPS "Bridgehampton hang gliders". I take the top off at the end of the day and put it back up the next morning. If its going to get real windy, I'll take it down. Here's what happened at NHIS when a tie down was attached to a golf cart.
That Yamaha tent must have been 100x100. I never did go back to see the damage to all of the bikes that was under it. I remember being up near the entry to the back straight and watching that tent flapping in the wind. It was surreal. The whole days was.