What you have to appreciate is that you have a hot Exhaust pipe less than 2" away from your leg.
When cruising slowly around town there is not enough air flow to take the heat away, it's just radiating outwards.
Once you get out on the open road and are at cruising speeds, the air flow past the pipe is sufficient to take that heat away.
As mentioned earlier, even a stock bike will run hot around town as they are set up lean for a start.
Yes a stock Rocket whether it is a 2005 or 2018 will have a hot right leg because the factory has the fuel set lean for emissions. You have to get your Air Fuel Ratio closer to 14.2 while cruising. I solved that heat problem with a Dobeck Performance AFR Plus. And as a side effect of installing this device, the bike gained 19 HP and 9 TQ.