Get used to riding on your own. Even if you are planning on riding with someone during the race, get used to riding in your own space. If you need safety in numbers find some riding partners that don't suffer from separation anxiety and ride near each other without the need to be in constant contact. Endurance events are solo events and the chances are that you will spend most of the ride on your own. Even if you plan to ride with someone there are going to be times when you become separated. In fact, you will probably have times where you just need to be on your own. I love riding on my own but it wasn't like that in the early days. When you are on your own you get to ride at your own pace without having to match someone else's speed or stopping schedule.
It goes without saying that you need to get your equipment choices optimised for the race. There is nothing worse than carrying something from the start to the finish only to realise that you didn't need it at all. How do you know what you need? Experience. I have improved in this department over the years but still haven't got it perfect. That said, I would rather take slightly too much gear than too little.
Leave your heart rate monitor at home.
It's a distraction that adds no value to your race. A heart rate monitor is a training tool. It's not that useful for endurance racing. In the short term you have to deal with cardiovascular drift which skews the reading. By days two and three all it will tell you it that you are tired which is consistent with how you feel.
I have had many conversations with people who think they have heart problems because they can't get their heart rates up when they have been riding for days. The funny thing is that no matter how I try and convince them that it's normal they aren't convinced. Most people understand the basic principle that we have a fixed volume of blood in our system and as exercise increases the demand for oxygen and nutrients our heart increases its rate to match the demand. Once you have shredded your legs over a couple of days the muscles simply cannot perform at peak and require fewer nutrients and less oxygen. Therefore, heart rate will naturally decrease. There's nothing wrong with the heart it is simply maintaining an equilibrium between requirement and delivery of oxygen and nutrients. I have watched people pack up and leave a race because they think they have heart issues when there is nothing wrong with them at all. Do yourself a favour, avoid unnecessary headspace scribbling and leave your training tool at home.
Rid yourself of the NEED for anything.
This point might be a bit contentious but hear me out.
If you are one of those people that need XYZ drink on the bike and ABC recovery shake every time you get off the bike, perhaps it's time to think about it rationally. If you really think you can't ride without them then what are you going to do on The Munga? Yes, there is an energy drink and supplement sponsor involved in the race and you can use their products. But here's the point - all you actually NEED in your bottle is a teaspoon of salt and a tablespoon of sugar. Salt for sweating losses and sugar for energy. Just sugar? Yup. Your muscles can't read labels and sugar is sugar no matter how you dress it up.
Don't get me wrong, I'm not suggesting that you ride with only salt and sugar (although I know people who do), just don't be fussy about what you use and don't have a melt down if you can't find the "right" stuff. By all means fill your bottles at the start with your sugar brand drink of choice and maybe take a few sachets along if you wish but it's not necessary. This is not a 3 or 4 hour race and I can assure you that even if you could carry your race juice of choice you are going to hate it after a few days. In summary, rid yourself of the burden of NEEDING anything and rather settle for what can be found along the way.