I'm very pale as well, and it is tricky to do a fake tan. I've done them a number of times, and there's a big danger of ending up with splotches. The only time i ever paid for a professional fake tan, I got the worst splotches
Another thing to consider: if you are very pale, it doesn't look convincing to do a dark fake tan. You need to just go a few shades darker than your original color. You will still have freckles. And you've got to be super careful to have your hands not be blotchy.
If I'm going to bother with a fake tan, I only do my legs and leave my arms really pale. The arms are harder (particularly with the hands), and usually in my case I'm just embarrassed of how incredibly pale my legs are in shorts.
How much time do you have before the wedding? You might want to start experimenting well ahead of time.
Another idea: what if you had a nice shawl or shrug that went well with the dress? You could put it on right after the ceremony. Note that I am not suggesting changing the wedding party's attire, just adding something for the reception. During the ceremony everyone is going to be looking at the bride and groom, not so much the maid of honor, so you could avoid scrutiny this way.