I know Terry was using two different types of coolers when I bought mine. I went to Lowes and bought a piece of 1/4" x 1" x 3 feet aluminum bar. I then made sandwich brackets to fit the top and bottom of the cooler. That gave the cooler a solid mount and allowed me to use spacers to keep the cooler away from the frame's powdercoat and any possible wear damage to the cooler's fins. The rubber strap mounts are used in two sizes - those on the sides (visible here) fit around the downtubes and bolt through as shown. The top ones are smaller and fit around the horizontal tube welded between the downtubes. This keeps the cooler rubber mounted and it's not going anywhere.
This photo is old, but shows the stainless braided lines and fittings available from Jegs and the stock horn mount. Since this was taken, I did the Carillo install and had the top and bottom aluminum pieces milled with curved edges at the top and round reliefs cut just above each exhaust header for a custom appearance and give a lot of clearance above the pipes to keep away heat. I also replaced the longer bottom bolts/nuts with shorter polished, stainless pieces.
Gordon