My screen install is very similar to yours. Try voice recognition as a partial solution. Of course, if the stereo is up loud or the windows are open, forget it, but for the most part it works very well if you have a decent microphone. It also impresses people and it really keeps your attention on the road. It's effortless.
Doesn't negate the need for steering wheel or remote buttons as the voice doesn't work when it's really noisy, but I've found it to be a great addition.
BTW, I'm using Bruno Speech Recognition.