I have an HD mini touring seat that sits me 2-3 inches further back when compared to my mustang regal touring seat. The mini-touring is good for short rides (1-2 hrs) but the mustang is the way to go for longer trips.
I'm 6'4" and have been using a Saddlemen Road Sofa for over 3 years and about 55K miles. Great seat. It moved me back quite a bit. If you order the Road Sofa direct from Saddlemen, they take measurements from you and will also tailor it to what you want. If you tell them you want to get back as far as possible, they will do it. See them here:
The Corbin moves you back about an inch or two and you sit a little lower too. I have it on an Electra Glide and my wife hates it because she lost room, and she's pretty thin! I've owned Corbin saddles for years and I like the support from them. When you first sit on one it feels hard but after it's broke in to your butt they are the only way to ride! I'm not into the Ironbutt rides but I have done over 700 miles in a day and could still walk.
I can say that the HD pillow style touring seat I just bought won't move you back. I wanted something like the original seat that comes on a road glide and my dealer had this in stock. I was more interested in lower back support than moving my seating position. I feel a little closer to the tank but as I put a few miles on I think it's more that my back isn't hunched in the wind anymore . Other than that I am sitting a little higher too. So far it's ok - my back has been thanking me for that upgrade since I rode home with it Saturday
i have a new corbin black stinger seat and backrest forsale. it can be seen at pwrtc.com/~klange/corbin.htm it sets me back about 2 inches. with my shortarms it just isnt for me. i am located in n/c ind. i will sell for 400$ +shipping
Found my new Mustang solo with backrest and rear wide pad on my front porch yesterday. Installed on RKC last night, felt real good. even made it easier to back up the bike with the backrest on. Will ride tonight to check out function. I noticed seat is just about 2 inches back and about the same height. Had to adjust the center console on the tank rearward to compensate for the seat being farther back. May have to go to Heritage bars to be able to assume the right comfort level in reach. Seems like lots of back support. Just what I was hoping for.
I just installed a Mustang solo on my '02 RKC and it moves your seating position back a couple of inches. I had already installed the 508 Chubby bars and with this Mustang seat it definitely puts me in the comfort zone.
I 3rd the Mustang seat for the Road King. I bought the seat pictured above and loved it since the day I put it on. It looks great and feels good on the rump. It will sit you back about 2" and lower you about 1 1/2"
Just to let you know, I sold my '00 RK last month but I kept the Mustang seat in hopes of another RK this spring. That is how much I like the seat!