Hi moemoe,
I would also suggest considering a mattress with thicker layers of latex and a higher density base foam both of which may be more suitable for higher weights. Posts #7 - #9 here from a day or two ago is also about similar circumstances and would be well worth reading.
When you can’t test a mattress in person I would always suggest a more detailed conversation with the manufacturer to help you make a firmness choice. They know more about their mattresses than anyone else and are in the best position to help you choose the firmness level with the highest chance of success based on “averages” than anyone (see mattress firmness/comfort levels in post #2 here).
As TandL mentioned … Brooklyn Bedding (Dreamfoam’s sister company) can also make a mattress that uses both latex and memory foam in the comfort layers (the Aloe Adele) and they also make a mattress with two layers of latex (the Aloe Alexis). I would also keep in mind as well that memory foam isn’t as durable a material as latex so the tradeoff may be comfort vs durability but with a mattress where you can exchange a layer then it’s always easy to replace a layer that softens or breaks down before the rest of the mattress without having to replace the entire mattress.
Phoenix