Dual Lock Fastener Tape (AKA heavy duty velcro). I've used this in a couple places where drilling and bolting wasn't an option. Very small patches will do the trick.
You'll also need a high pressure line to connect the tank and regulator. Paintball suppliers are probably the best source.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk