Help finding soft and very cool mattress for side sleeper.

I like a soft mattress but am an extremely hot side sleeper. Even in mid winter I get hot. Dont like the clingy feel of sinking into memory foam (as well as heat retention of memory foam). I am 167kg looking for a king size mattress. Have had all sorts of problems in the past with finding the right mattress especially with heat reflecting back from the mattress. Can you help?