Roof Rack

Just curious is anyone has added a roof rack for storage (?) to the roof of their cargo trailer conversion ??
Thinking one of the luggage containers could be used for storing lawn chairs, pop up canopies, etc. on the roof ? I know that we have lots of room in the trailers for storage.. But there may be times when you get to your destination in the middle of the night, or staying in a Wal-Mart parking lot, etc. and don't want to have to unload the stuff from the trailer, just to go to sleep..
Also thinking it may be a good place for the spare tire/wheel ??
Thinking one of the luggage containers could be used for storing lawn chairs, pop up canopies, etc. on the roof ? I know that we have lots of room in the trailers for storage.. But there may be times when you get to your destination in the middle of the night, or staying in a Wal-Mart parking lot, etc. and don't want to have to unload the stuff from the trailer, just to go to sleep..
Also thinking it may be a good place for the spare tire/wheel ??