3. Other Items to Make Your Day More Comfortable

In no particular order:

Something to clean your visor or goggles with.
Perhaps some safety glasses to use as a backup instead.
A spare pair of gloves in case yours get wet or muddy.
For base layers please apply the principle of layering - we will not be moving fast, and you may get hot.
If the weather is forecast to be particularly cold or wet please consider a waterproof over jacket (for the reasons given above you will probably not use it, but better to have it and not need it).
If you have a camelbak style drinks bladder please bring and use it, we will be taking regular breaks but it can be nice to have a drink with you.