I have used the chocks between the tandom wheels on my trailers for years. They are fast and do not rely on staying in place on slippery wet grass. I still use 2x 6 x 18 and 1x6 for leveling but the plastic blocks are cleaner. I do have big plastic chocks for the truck, if I am going to jack it up.
We have used the X-chocks for some time and are very happy with them, they can't slip. Also changed to 16" wheels and tires and the X-chocks fit perfectly, I don't know if others will fit in the narrow space.