I know there are numerous older threads on this topic. I promise I have read them. I have learned a few things, stall mats, golf carts, 15 min unloading, etc.  But I am still feeling super overwhelmed with whether or not I'm "ready" for such a big event.  I would be going with an experienced group, so that's huge.  So splitting fuel, staying onsite in trailers, NMNQ entries, a jacket... am I missing a glaringly huge additional cost? 

I feel like It's going to end up being thousands of dollars to attend for some reason and I want to know up front what i'm getting into. :) lol 

It would be my first super show.  I'm nervous already and I haven't even sent entries! 

Are you entering the finals or the NMNQ race?  Your entry form will show your expenses as far as entry fee, processing fee, stalls.  There is an area to enter side pots as a choice, not a requirement.  Stall mats are extra or if you own some you can bring your own.  I like them but they are expensive so I just bed my stalls really deep and my horses haven't had a problem.  The rv spots are limited but they are reasonable.  The regular lot is anyway, the ones by the barn on concrete are nice and have sewer hookups but they cost a lot more. 

This is a pricey race to enter but the payout is fantastic.  It's a blast and I never miss it.  Going with experienced partners is a major bonus for you, they can help you get your feet wet! 

Be prepared for the most organized chaos you will ever experience. We went for our first time last year and had an absolute blast! Didnt win any money but had a fun time. There is alot of walking involved. Know your draw number and dont forget they run in reverse order the 2nd go. I almost missed my 2nd run cuz I didnt realize what number they were starting with. 
Im not sure how much we actually spent last year. I know I was at $500 by the time I paid entries, bought stall mats and shavings. My husband paid for fuel and the hookup. 

The only thing I would do different is bring a set of wheels to get from the barns to the rv park faster. I walked most of the time and my legs hurt so bad. And I will probably get a tack stall. Havent decided yet. 

Just go and have fun and dont stress. 

I think you could save a lot of money if you brought your own food/drink to keep in the trailer.  

LOCKS. LOCK your trailers, scooters, trucks. and hide your valuables in your trucks. BBR people are great. the trash of OKC are not so much. My friend had her truck broke into and stole her purse.  Its a great race and pays so so well. Ross and her crew are wonderful to deal with. You will have such a great time. 

Bring some lawn chairs/reclining with foot rest and ice chest so you can relax at your trailer and enjoy some ice tea/drinks, we always set a canopy between two trailers so we can sit and relax and take naps while inbetween races, never been to the one that you are talking about but I use to go ANHA and these always was a good time to bring along. We always had a small pit to cook on to.