You could get someone else to carry the spares around for you!
In the kit reviews for the Louis Garneau Vorttice, as the thread got derailed slightly, I queried CCS's policy of why carry fluid for a ten mile TT. The answer was simply a dry mouth, which leads on to whether to race with discomfort for a short while or take a small hit for time by carrying something or putting on an article of clothing, but go quicker by being more comfortable. Another example is socks, risk blisters by not wearing and then go slower, or put them on add 30 secs but run quicker for longer, can you make up those 30 secs.??