Just make sure you keep nutrition up - if it is a looong ride, I would start eating about an hour in, and eat every half hour. I don't eat much, just half a muesli bar at a time - unless I feel hungry and then I eat a whole bar.

The longest ride I have done took me 4 hours and that regemin of eating was enough. I may have needed something more substantial if I had had to output more power (it was a training ride, not a race) or if I was going to be longer in the saddle.

LOL, NMT, I hadn't thought of that as a reason for no second hand seats...