Would the seats fit into a very large garden refuse sack? If they do then just stick a vacuum cleaner on the end and tape up after it has collapsed. If not then just rap up as much as you can with liners from each end and physically remove any excess ballooning and tape off any gaps. If they are off for an extended period in the garage, then look out for mice. They can do lots of damage. So sealing of is still important and trying to lift them a little off the floor may help.