Hi there. If the bedpost is smooth wood, the ferret will not be able to
climb it. However what they will climb is the blanket if it hangs over
the edge. As far as the gap between the mattress and headboard...stuff
it with pillows or a blanket so they can't slide through and get
squished.
Boxsprings are a challenge as well. The ferrets get up into them and
hide things and dig. I have plywood under my box spring to keep the
ferrets out.
[Posted in FML issue 4607]