I would like to mount two small flags on the back of my 21 Freewheeler trike. I don't want to drill any holes. I have the OEM sissy bar/passenger back rest, but I rarely have it mounted and it's usually in my garage. What are my no drill options to mount the flags? Is a sissy bar luggage rack my only choice? Is there a particular rack you suggest? I looked online and found all kinds of racks for the Touring trike, but not for the Freewheeler. I'd appreciate any suggestions.