Enlarging a Luggage rack

[catken]

I have a small Harley luggage rack which works fine for transporting small items. However, when out touring with my t-bag, the bag drapes over the rack hiding my license plate. Would like to expand the size to accommodate my t-bag some how but be able to put back to stock when not needed. I also want to make sure it does not scratch the rack I have on it. I welcome any ideas.