My RV came with several pads made by the previous owner, all made with 3/4" OSB in 3 sizes: single 3/4", laminated 3/4" (1 1/2"), and laminated 3/4", 1 1/2 2x12, 3/4". Each pad has a 1" screw eye on one side and the thicker ones have a handle as well. The eyes are convenient to position the pads under the jacks without climbing underneath and great if it's raining when you pull them out. The screw eyes are easily caught by the awning handle, making a dual use of the single tool.
They've been treated with Thompsons water seal, and don't seem to be de-lamainiting with age.