Are you doing WS 100? I had a marathon run coach a while back who had several silver buckles. I always had half a mind to do something like that. Trail running (especially at those distances) is really basically super fast hiking, something I have always loved.
Since I haven't done anything quite like that, running-wise, I don't have event specific advice, but some basics from ultra cycling seem to carry over:
1. Run to the next check point, aid station, mile, top of hill, whatever. Don't look at it as a 20 mile (or whatever) day. Look at it as a series of one mile days.
2. Stay hydrated with good electrolyte replacement - especially given the heat. and hydrate SUPER well this whole week, also with electrolyte drink as opposed to just water.
3. Pay particular attention to your hydration on the plane and in the airport. AFTER the training weekend, please rehydrate well before getting back on a plane and once on the plane, be sure to get up and walk around every hour or so. There's plenty of anecdotal evidence suggesting endurance athletes may be more prone to DVTs - especially after an event. See Velogirl's article: http://www.velogirls.com/resources/publications/dvt.pdf (It happened to me also.)
4. Have fun!!!
Good luck! Let us know how it goes.