Hi Sofie,
This would be a preference choice that would depend on whether a thinner or a thicker mattress would be a better match for you in terms of PPP. A mattress with more layers would also provide more options to customize the mattress both before and after a purchase as well. There is more about the pros and cons of a thicker mattress or a mattress that has more layers in post #4 here and the post it links to but one of the most important parts of buying a mattress online that you can’t test in person is a more detailed conversation with a knowledgeable and experienced manufacturer (such as SleepEz) who can help “talk you through” the options they have available that would most likely be the best match for your body type, sleeping positions, and preferences and that would have the best chance of success (see mattress firmness/comfort levels in post #2 here).
As long as your platform bed meets the guidelines in post #1 here for an all latex mattress and the slats aren’t too far apart and it has good center support to the floor then it would be fine.
Phoenix