As I've said ad nausium on this board, I'm planning on getting my dress custom made, because while many designers go up to larger sizes, I have yet to find one that does a 38" inseam (the add extra length option only adds it to the bottom, and even then, doesn't add enough).
When I was in Junior High, I was in a few community plays, all directed by the same volunteer who coordinated and directed everything. She also made the costumes. Her creations were the most beautiful, intricate, period Victorian costumes I (and my family) had ever seen, and I've always held the tiniest hope that she would be willing to make my wedding dress (for payment, of course). I know it's a long shot, but I still have her address, and wrote her a heartfelt letter asking her if she would be willing to sew it (expressing all the way through that I won't be offended if she declines, because I know it's a big project), because I want her to have plenty of time to a)think about it, and b)make it if she agrees. I just finished the letter today, and it's going out in the mail! Long story short, please cross your fingers (you don't have to keep them that way, haha) that she says yes!