we have a3513 and there is only one drawer at the foot of the bed.
It came with a king bed, very uncomfortable, so i converted it to a queen size to fit a regular queen size mattress.
This also would give us much more walk room next to the bed.
doing so, i had to remove the plywood and discovered all the unused space.
I cut a nice rectangular opening on one side and now can access all this wasted space for storage.