The use of battens has been previously touched on to promote airflow under mattresses to avoid condensation and mildew in an earlier post. That was on a much thicker mattress which absorbed the lumps of the battens and still allows a comfortable nights sleep. On thinner mattresses, the battens would be horrible lumps in your back that would lead to a horrible nights sleep.
The use of a plastic trellis will help distribute the force and keep the mattress elevated to promote proper airflow while keeping the mattress elevated yet flat, allowing comfort without moisture under the mattress.
If you find yourself with moisture under your cushions, this trellis and batten system will be an economical solution to your mildew problems.