Then get a hitch mount cargo basket
MeeFar Folding Hitch Mount Cargo Carrier 60" X 20" X 6'' + Waterproof Cargo Bag 20 Cubic Feet (59" 24" 24"), Hauling Weight Capacity of 500 Lbs and A https://www.amazon.com/dp/B09G6L487Y/ref=cm_sw_r_cp_apip_o53mIhOtd8tqn
It was a joke. Do not JB weld it to your roof it will be on there permanently. Those boxes are specifically designed to be mounted to a roof rack.
You could put 2 pool noodles on your roof and use some cam buckle straps ( do not use ratchet straps they will crack your top. ) It will get you by but is not ideal.
Most Jeep owners utilize a hitch mount cargo box like this:
MeeFar Folding Hitch Mount Cargo Carrier 60" X 20" X 6'' + Waterproof Cargo Bag 20 Cubic Feet (59" 24" 24"), Hauling Weight Capacity of 500 Lbs and A https://www.amazon.com/dp/B09G6L487Y/ref=cm_sw_r_cp_apip_xkDJHcs2UIFuh