I have done it 3 different ways
1. J hooks for rubber bands.... store bought 4-40 J hooks are horribly expensive
--- ON one I just drilled 4 holes through the fuse and put in long pieces of music wire, bent over on the inside of the fuse, then cut and bent to length on the tank side
--- Did not really like the look of the wire from hole to hole on the inside BUT was fast to set up and worked well
2. Home made J hooks but epoxied in on the Tank side only...looked and worked well
-----but both options I used rubber bands that deteriorate....never did get a stash of large -O- Rings
Some comments on a forum that Ply or aluminum can be successfully glued to the back of a plastic clunk tanks. Then set up with two elongated holes to mount and adjust...the adjustment mounting slots can be fore and aft, or top and bottom, depending on real estate on the outboard or inboard side
I took a fresh Hayes tank...cleaned well and 100 grit sanded on the back side..then cleaned again and set my ply wood mount to the tank with J&B epoxy. Then fuel proofed the ply with thinned 30 min hobby epoxy
------Two years of infrequent flying... has not de-bonded yet, and still looks the best of my methods
I personally do not like working with wire ties, but see that a LOT of folks use that method