The problem is NOT ventilation. The problem is lack of damp barrier!!
As close to the warm body as possible you should insert a damp barrier. Easiest to understand is a plastic shield. In wooden houses it is used in the walls/Cieling etc. and best is to place it just elow the sheets
. But you won't lika that of course!
So if you can find a "bed protection" with breathing functionality what is used in hospitals and baby beds - and put that below the sheet, if you have a topping matress you can put it between a thin top matress but on top of the thick mattress.
Why this? Well, the warm air close to your warm body can absorb a lot of humidity. When this air (damp) transport itself down the mattress towars the cold surface (hull is colder than your body), the air gets slowly cooler the closer to the hull
you get. And the same experience you can see when you take a cold beer
can out of the fridge a warm sunny day - it gets wet on the outside - the same is the reason you get humidity below your matress. The bottom of the bed is the bear can!
IF you var a lot of holes in the bottom of the bed - the transportation will continue further down... and the water will be found on the inside of the hull
. But as long as the bed is "solid" no expensive froli system will make any substansial different, exept in your wallet!!