I wouldn't draw them all the way! You'll crush the tank. I tighened mine until they were nice and snug, then I hit it with *maybe* 2-3 turns more.
I also placed a piece of FatMat across the top of the tank to insulate the metal-to-metal contact to prevent gouging or scoring.
I cut slices in it and laid it down over the depression.
Then I snugged it all securely. The only thing I wish I did (and still might do...) is lay a piece of rubber onto the straps before installing them.
Hope this helps!