It has been done (using the BBQ bracket to support a shelf instead of a BBQ). Use the Search function at top right and type in: outdoor shelf. There are several threads dealing with this.
2015 Shamrock 231KSS, Oyster shell
2016 Chev Silverado LT Z71 Ext. Cab, 4x4, 5.3L V/8
Reese Straight Line WDH, 2000W Honda Gen.
2 Old Town kayaks & 2 Boston Terriers - Zoey/Gonzo
Lar & Ruth
55 nights camping in 2015, 45 in 2016