Let's face it, as noble as your intentions may be, if you need to run anything beyond, guitars, bass, drums, vocals, and keys, you are initially going to be perceived as a pain in the ass. So you had better come prepared. If you do come prepared, and you manage to make the Front of House mixer's job easier, you will have won his/her respect, the respect of your peers, give off the appearance of being a professional outfit, but most importantly, you're more likely to have a go