3D Spacer Mesh is available in this maker friendly (generous back length) size.
Suggestions for the first time you use this product:
Allow the mesh to “relax” on your cutting table – maybe even give it a bit of a massage before you mark out. Then go and relax yourself for bit, check your dimensions and right side up. Return to your work and measure again before cutting. Vacuum or sweep up the shavings.
Once the Mesh is anchored in a seam it will sit beautifully in your project and is quite robust.