Over-active: take comfort from knowing that Stuart has set some really great checkpoints and the aim isn't to catch you out, but to allow you follow the natural flow of things and take in some good trails. As Chew says, you don't need a computer. Mark your checkpoints onto a map and link them one a time, avoid looking at the big picture. You'll soon see a route emerging. There are a number of bothies on the route too, so if you suddenly decide you don't fancy the bivvy bag or you want to make a brew out of the sun/wind/rain, you should be able to do it under a slate roof.
In a way, a month to plan things makes it a bit harder. I'm reminded of when I've done Polaris (two day orienteering event with an entry fee and rules…) where you get the map the night before and the active checkpoints for the day AFTER you start. You get about 10 mins tops to plan your route for the day, and then have to ride to the clock. This will be much more chilled, I'm sure.
For packing your bike, try and keep the heavy things as low down on your bike as possible. Strapping stuff under the handlebars is good, or under the saddle if it's not too heavy. Put exposed or critical stuff like spare clothes into a Exped dry bag or something similar.
Beards are optional…