I have a 2008 FXDC, and I am almost 100% positive that the stock bars are the reduced reach bars. The harley catalog says that those bars seem to be the most comfortable for the Dyna line of bikes, and are OEM on the FXDC. The pullbackrisers might help your predicament, but you've already got the bars on there.
I've questioned this before, because I want the opposite of what you have...I switched to the Sundowner seat also, and i feel like I'm sitting in an awkward position where I'd either like to be leaning back further, or leaning forward, but I'm stuck in a middle position that causes my low back to be sore. I'm looking to get a set of bars that will pull me forward so I'll be leaning over a little bit. I've got my FXDC setup just like yours...sundowner, mid controls, highway pegs. One thing I noticed about the highway pegs is that they are too close to the bike, and I need larger pegs. I feel like my feet barely fit on there, and I have to force my feet to stay there. A set of highway pegs that maybe sit further forward and stuck out about an inch or so wider would probably solve it.
Oh...and usually, if you go + or - a few inches with bars or risers, no change of cables is necessary.