Hi zumba,
It would depend to some degree on the construction and strength of the foundation and the amount of sagging it allows (some wood and types of construction are stronger than others) and whether it has good center support to the floor underneath it but I would say “probably yes” it would be fine and it will also even out the support surface enough that it would likely be OK with sagging in between the slats as well.
I would tend to choose a support surface that allowed for better airflow under the mattress (see post #10 here).
Another alternative would be a slat conversion like this which would be more rigid yet and also allows for airflow under the mattress. Pegboard would also allow for more airflow under the mattress than a sheet of plywood.
Phoenix