Playground sand is handy, and usually easily available. The smaller bags, usually 30 or 40 pound sizes, are handy; but the bags it comes in are only intended to be strong enough to keep it "mostly in the bag" until you get it home and sometimes by the time you're ready to take it out of the truck (or the "boot") you end up shovelling loose sand.

In my area you can also get "Truck Sand" or "Pickup Sand" bags of about the same weight, or up to about 60 pounds (or more) per bag that are in an elongated heavier bag intended specifically to stay in place better in the truck and to resist getting punctured if you load/carry some actual cargo during the season of use. Since these are seasonal, price is extremely variable, so they may or may not be a bargain.

If you're getting the playground sand at a "lumber yard" you can probably also look at the construction sand bags down near the quik-crete area that get you 50 to 90 pounds per bag at about the same price as the 20 to 30 pound(?) "playground sand" bags. The bigger bags will probably be cheaper, and are just as good for ballast but may be "quite a grunt" to handle.

Your choice depends on what works best in your truck, and with the way you use it; and you need to consider both the winter driving effects you're trying to get as well as how handy it is to take the ballast in/out or to work around it during a brief thaw in the weather. I find anything over 30 or 40 pounds a bit "unhandy," and smaller individual bags (you can always use more of them) may be better for those who might want to balance out a smaller SUV or passenger car.

Addition of the hydraulic liftgate on my p'up added about 250 lb to the tailgate end ('way back past the axle) already, so I don't really need much additional ballast to get to fairly even loading. Extended cab pickups, and a "topper" or toolbox on the back can have a big effect on the fore/aft weight balance, and about the only way to be sure how much adjustment might be helpful is to actually weigh the vehicle, preferably on a scale that gives individual axle weights.

Many "truck stop" scales will give you three individual axles so you can get a tow vehicle and trailer loadings all in one shot, althugh not all truck stops have a scale. The fee (about $5 US?) usually covers one weighing and a second "weigh back" any time within 3 to 5 days. Most don't object to "little bitty cars" getting a weight as long as the scale isn't crowded, but you may need to "press button to notify" out at the scale to get the attention of the clerk who prints out the result - and the button is usually at about the right height so a semi driver doesn't have to get out to push it - i.e. about 9 feet up from where "itty bitty car driver" sits on the scale. (Take a ladder?)

Many small cars could benefit a lot from a weight/balance adjustment specific to snow driving, although it's probably not worthwhile unless such conditions are reasonably frequent or last quite a while in the area.

John