That is one ugly Road King.
I think they spend a lot of time not putting front end touring stuff on it for a reason. I think that Buick radiator is the problem. These bikes may overheat easily if you do anything to block or reduce air flow to the radiator.
That rear cylinder probably gets super hot so they need a super liquid system. You generate some heat spinning a 27lb crank shaft all day.
I am sure the engineers have worked a lot on loosing that radiator configuration over the years with negative results. It probably needs that big thing just the way it is or in a traffic jamb the rear cylinder takes a dive.
