I pulled the covers off of my v-berth cushions just a few weeks ago. My intention is the have the covers dry cleaned to prevent any shrinkage.
As for the plastic, I think the purpose of that is to allow vacuum to be applied to the padding before being inserted into the covers. Applying the vacuum w/ the plastic covering will shrink the cushions and allow them to go in easier.
When I get my covers back, I'll try putting the cushions inside a large trash bag and sucking the air out with my shop vac. If that doesn't work, I'll have an upholstery place put them back together.
That being said, how would you guys recommend I clean the cushions themselves? While they don't smell bad, I would like to freshen them up a bit.