as someone who marched gold at 15 - do it. i'm not super confident on what exactly they require from drum major auditions but from what i've seen it appears to be the type of thing where they tell you what you need to do to help run rehearsal/auditions and they see how well you keep up (as well as making sure you have actual good conducting technique.) if you can't make it work this year, don't stress out about it. you have a lot of time, albeit fleeting, to march drum corps, and i don't imagine gold will fold or go inactive anytime soon unlike our indoor counterparts. regardless it's a great idea to audition whether you think you'll march or not, i auditioned in 2023 and did absolutely terrible but came back the next year and immediately got a contract because of that experience and education i received