Yup the manual stinks.

I put the tank on the nose as the manual shows in the pictures.

I put foam around the tank and the wood formers where they would contact the tank.

I believe I built a small hard ply "tray" for the tank and used both foam and velcro to hold it in place. Usually I epoxy the tray in place, as this will add more airframe durability and strength.

I then put in a small cut to size sheet of ply, screwed in against one of the formers to hold the tank against slipping backward. e.g. it's up against the back of the tank, with a small piece of foam glued right on the wood. The foam butts up against the back of the tank.

I usually do this in place of any permanent epoxied wood restrainer as you NEED to periodically replace the tubing... ( it is a good idea to do this prior to each flying season ).