Great strategy Pete, some training will make all the difference. My suggestion would be to consider a buildup over time to develop your ride fitness for the day. That is, a slow buildup over time so you peak on the day.
When you try some longer rides keep an eye on your body. Test out some different snack foods (Oat bars and Sultanans and dried pineapple are my faves) that give you the energy you need without upsetting your stomach or having to eat fast food along the way. On single day rides I have breakfast before I leave and eat from the top box until a stop 8.30pm/9.30pm when I"ll have a plain burger and one coffee.
On your training runs take water with you so you get the feel of how much you need to drink to balance hydration and too many pit stops. The more you take with you the less time you'll need to spend ratting around servos looking for something you might like. I generally eat while refueling and paying for it.
If you are a coffee drinker go on one of your longer rides without having the morning brew, if the headache and nausea come you might need to think about weaning yourself off it before the big one (along with the alcohol and recreational drugs if yo indulge).
On your test rides see if you can develop a routine when refueling and make a mental note, or a written one, about how long each stop takes and see if you can make them quicker. Practice your routines on your short rides too. This includes getting your dockets, checking them, writing the ODO reading on them, securing them and keeping a log suitable for IBA submission. It even includes gloves, helmets, earplugs. I've seen people ride off on the last legs of long rides without their gloves. I've seen people helmet on, forgot the plugs, helmet off, "what did I take the helmet off for?", nah, helmet on, forgot the plugs, too late I'm going. The latter used to be me although I now would take the helmet off again and put the plugs in.
If you take, or are thinking of taking ibuprofen or paracetamol (I never do while I'm riding) or use it for another reason be aware of it's effects on your body. On the test rides think hard about anything on the bike or gear related that annoys you and see if you can sort it.
I have no doubt that pretty much anyone can turn up on the day and ride an ST 1770k's in 24 hours, it's really not that hard. Riding with others, in my experience, helps with fatigue because you can take turns just following along and rest the brain a bit. But getting some of these basics right will help make the big day easier and much more fun for you.
Like TJ, I treat this as a sport and I adopt the same strategies for LD riding that I do when I train for half marathons and marathons. The principles are the same. Hydration, nutrition, don't go too hard and don't waste time at drink stations, oh, and train.
There's more, but it's great to see people thinking about this stuff.
