Denise,
Here's my 2 cents worth:
Personally, I would never intentionally eat gluten, because gluten has the potential to do much longer-term damage than the other food sensitivities. Most antibodies to food-sensitivities have a half-life of only 5 or 6 days, so their antibody level decays fairly rapidly. Gluten antibodies, on the other hand, have a half-life of about 21 days, so that means that higher levels of anti-gliadin antibody production will persist at least several times longer than the antibodies to other foods.
That doesn't mean that you will necessarily react for a significantly longer period of time, though - it simply means that your immune system will be kicked into a higher level of alertness for a much longer period of time, (implying that the T-cells that are the source of most of the inflammation associated with MC may continue to be produced for a much longer period of time).
That said, you will probably never have a better opportunity to "rationalize" a gluten challenge for the purpose of determining just how you might react to a sizable dose of gluten, if you care to check that out.
The other food items, (anything other than gluten), usually produce a much lower risk of intestinal damage, so they are much lower-priority items, IMO. IOW, what I'm saying is that the other food-sensitivities are not a big deal, (in terms of potential intestinal damage), compared with gluten. The immediate reaction might be just as severe, (or even worse), but the longer-term risk of a setback, due to intestinal damage, should be significantly lower with anything other than gluten. As we all know, though, we are all different in the ways that we react, so my opinion is definitely not chiseled in stone - YMMV.
If I were in your shoes, I would probably give a lot of thought to what Polly recommended, depending on my reaction pattern to eating any of my food sensitivities. IOW, if I typically reacted within a few hours of eating, I would probably want to postpone the "punishment phase", until after all the excitement of the occasion was past. If I typically didn't react until the next day, then if I had decided to "indulge", and throw caution to the winds, I would probably dive right in, with everyone else.
Good luck, whatever you choose to do, and enjoy the occasion. If you decide to go through with a challenge, please post a play by play account of how the events unfold.
Hugs,
Tex