There are lots of opinions and experience out in the RV community about the best way to mount the oil cooler. Mounting the oil cooler per Van’s plans appears to be a recipe for replacement of the baffle support later on as the support allows a lot of flexing as the engine vibrates.
My approach was to create a very beefy mount that allows more air flow through the oil cooler. The standard mount has the oil cooler mounted directly behind one of the rear cylinders, and the cylinder itself blocks cooling air flow. So, in addition to installing 1/8″ aluminum angle to strengthen that corner, I also added 1/8″ aluminum U channel, which not only added strength, but spaced the oil cooler away from the rear cylinder an allowed me to lower the oil cooler to avoid interference with the cowling.
Finally, I added a corner brace with some 4130 steel tubing I had. It serves to tie the rear corner baffle to the left rear cylinder. Since that part of the baffle structure primarily vibrates with that cylinder, it makes sense (to me anyway) to tie it all together. Testing and time will tell the tale!