Extra weight will be punitive with respect to accomplishing the navigation stages and some teams take steps which is more extreme than I feel comfortable doing given my testing results with different types of equipment and others might gamble on how critical that item will be in the race. There are a couple of podcasts on the Precision Rifle Podcast channel where they talk to multiple time winners of the event (Tom and Dave) and Fredrick Barton of Bison Tactical who went from an RO to being a top 3 finisher last year. The types of non-navigation challenges are different from year to year, so it is difficult to know what "extra" equipment might be beneficial to carry for that year's race. There are also some blog posts that talk about people's experiences, gear list, and what they learned.
Beyond that, make sure that you are familiar with how the items you are carrying work and that they are durable. If your water filter goes out, you could be in trouble depending on the weather and location.
Lastly, get as good as you can on the land navigation. The organizers do not always make it easy to find the checkpoints even when you are in the right place, so you have to be certain that you are in the right place or else you may spend a lot of time searching.
It is a great race and fun in that painful sort of way