Tips on making a synthesized space sound bad?

Pretty much what the title is.

I am involved with an organization on my campus that does a fashion show every spring. It is hosted in our school's gymnasium for a large crowd, with students making all of the fashion pieces, lighting, and specifically: the sound/music.

One of the issues we run into every year is that the music is not mixed properly for the space, considering that people go from working on headphones/monitors, to premium-grade hanging stadium speakers. It is impossible for us to get more than 2 hours per person in the space before day of show, so mixing within the space is pretty much out of the question.

My goal for this year is to build a simple-ish effect chain to simulate the space of the gym so people can run their music through it and mix accordingly.

tl;dr

What would y'all recommend for an effect chain to simulate a gym? The space is incredibly boomy, with the low-end needing to be tamed a lot before the day of show. The space is the size of 2 full basketball courts if that weighs in at all.

I know it can't be perfect, but I just want to get as many thoughts and ideas as possible while I try to work on this, because I want the music this year to be as good as possible.