SOme of the roadsters remove the (mufler-cats) cats and go to tors(triumph off road mufflers) to give it more sound,less heat and lighter. and then put a tors tune on it.
there are a lot of different pipes but i think most of them cause more heat,
as for the temp gauge i think it was a matter that they just wanted to keep it simple. the temp lite seem to work for them and i have not heard of any one over heating. just us riders
if u do a search u will find threads about heat clothing ect it has all been covered with many good opinions and advice on what to buy ect.
myself i ride to work is 10 miles so i can tolerate some hot weather for that long. if i am going on a longer ride i try to get an early start to beat the heat.