There’s a couple of YouTube vids showing using a ratcheted band strap tie-down around the tank and setting the ratchet body position - when you turn the bolt there is a timber brace going to the wall from the ratchet head in line with the tangent to the tank face and thus the line of force - all you need is a spreader plate on the flat of the wall between studs so the brace doesn’t punch a hole. Those tie-downs are what are used to tie cars down to tow trucks with a 2” wide strap - if the strap slips you can always run a band of double sided tape around the circumference of the tank under the strap to prevent this.