Hi bobfrog,
I don’t know the specifics of the Denver Mattress “box spring” you have but I believe they only sell foundations not box springs (that have springs inside them that flex under the mattress). There is more about different types of support systems that are generally most suitable for different types of mattresses in post #1 here and a latex mattress tends to work best on a support system that has little to no flex under the mattress and that has enough surface area and small enough gaps in between the load bearing surfaces to prevent the latex from sinking or sagging into any gaps in the support system over time.
If you have a “wire grid” foundation then there is more information and suggestions about wire grid support systems relative to latex mattresses in post #10 here that may be helpful.
A solid surface platform would be fine in terms of providing good support under a mattress but it also reduces airflow under the mattress which could add to the risk of moisture retention and possible mold or mildew issues under any mattress (not just latex) although it may be fine as long as there aren’t additional risk factors involved (such as using the mattress in a basement or in a more humid environment). There is more about solid surface support systems in post #10 here.
Phoenix