I also have a bad back and I've had both Heritage and Road King. I still have a Road King, I found it to be much better on my back in the long run. I did change the seat right away because the stock seat had me pushed too far forward and I felt like I was right on the tank. A Corbin leather seat that put me back a bit made all the difference in the world. In my own opinion the RK is also more nimble and better handling than the Heritage was. YMMV

 

Road King put a back rest on your seat and ride. Then trade the Road King for an Ultra and enjoy pure heaven 🏍🏍