I started with 12 x 12 x 3/4 inch plywood.
So I did this next best thing. See the photo below. Qty. 2) 12 x 12 x 3/4 which makes a top and bottom. Then I added 2 pieces in the center. This now gives me a height of 4.5 inches high. This is my starter block for my levelers. I always put these down before I lower my levelers to the ground. This provides a stable base on dirt, sand, soil and rock. I even used them on hard concrete, if we are staying in one place for an extended amount of time.
In case I need extra height, I use Qty. 2) 2x4 with a notch cut in the center.
I place the 2 x 4 as you see, and then I place another 12 x 12 x 3/4 plywood on top.
This now gives me an extra 6 inches of height for my leveling jacks. By doing this, it is easy to carry, light and strong.
Finally we purchased 3, boxes of these 2 years ago. Each box had 8 inside.
So what does this mean. We can level front to rear or side to side even if we need to raise the rv 4 inches.
As I stated we started with total of 24 pieces. This allowed us to drive our wheels up to 4 inches higher. While we were in Longmont, CO. We stopped by a CW and they had a box of 10, for a special price. So now we have 3 boxes of 8 and 1 box of 10. This now gives me the flexibility to level in even the most extreme cases while boon-docking.
Then by using the wooden blocks I made and placing them under the leveling jacks I do not extend my leveling jacks to there full length, which I don't like to do.
So, lets say, I place yellow blocks under my front tires. Since each block is 1 inch and I make a stair of 3, this gives me a 3 inch higher in the front than the rear. Next I place my blocks using the 2x4 cross cut. Now I extend my levelers, and they may extend only 4 to 6 inches.