Hi Robalo247,
You are certainly not in a weight range where you would “need” 4 layers but you may still prefer it. There is more about the effect of thickness (either in a layer or in a mattress) in post #14 here. There would be no difference in terms of durability.
The best approach to choose the design of the mattress and the firmness of the layers for a mattress that you can’t test in person would be a more detailed conversation with the online retailer or manufacturer of the mattress you are considering so they can help help “talk you through” your firmness choices and the options that would have the best chance of success for you based on averages for your body type and sleeping positions (see mattress firmness/comfort levels in post #2 here).
Phoenix