I just did this in my truck and my Pioneer still works when extended 12ft. Your Alpine looks like it will work fine with extending it.
I'm using a 6ft vga cable that had 1 male end and 1 female end. So I just cut it in the middle and soldered the end wires to the deck, then I can just plug the connectors into each other to connect everything. I can also add extension vga cables easily if I wanted to run it farther.
I'm using a Pioneer 700bt.
I'll post some pics of the process later tonight.