Have the plot owners who have silos on them be able to rent them out to other players, both parties would benefit from this.
It could go like this:
1) 1 day rental = 5s for a T2
a) 1 day rental = 10s for a T4
b) 1 day rental = 17s for a T6
All silos should have a maximum of a 3 day rental and should the renter forget about the silos being rented, the contents should be deposited into their vault just like when the consignments end, or the plot owner gets to keep a portion of what is being stored.