I find that the header tank needs to be positioned relative to the centerline of the carb but the auxiliary and larger tank can be positioned anywhere as long as fuel is transferred and the header tank remains relatively full.

I have never flown with auxiliary tanks mounted higher than the header tank but have observed that gravity will drain fuel to the engines when they are not running. I recently observed a beautiful three engine Italian warbird with a significantly higher center tank for the outboards. At engine shut down the fuel lines were clamped. The novel approach seemed to work well.

Whatever you decide ground testing a few tanks of fuel and observing the fuel transfer will be important. It is easy to get something wrong that might create a disaster in the air.