Sandbags in pickup bed, placement?

There is no argument. Sand is more effective at the tailgate, meaning "you don't need as much" as over the rear wheels.

You don't WANT to use more than necessary, because the more you use, the more you have to stop. In other words, if all that weight gets to sliding, front or rear, it's more weight you have to stop

Too much weight can indeed act as a lever and start to lighten the front wheels, and too much on a long bed (such as extended van) can act as a weight out there and "swing" the rear around if you start to fishtail.

If possible you want loose sand (not frozen) so you can shovel it under the tires for traction if stuck.

CARRY CHAINS, blanket, food, extra clothes, tools, boosters, flares, shovel.

A 25ft nylon rope (one that STRETCHES) is good, better than a strap, NOT those cheap yellow plastic ropes. Better to have a good tow hook up front, hitch ball in rear so you have something to easily hook onto.

I've pulled a LOT of larger vehicles out with a rope, back in the 340 powered FJ-40 days, and even a few with my (cough gag) Ford Courier.

I don't pull people out, anymore. Screw em. They have cellphones. Let'm sit there. They brought their beer instead of their snow tires. They brought their RAP CD's instead of extra clothes, and brought their "I can drive past you" attitude instead of chains and a shovel. Screw em.