First the "official" response, talk to your coach.  They are trained to answer questions like this.  From my experience hyponatremia is usually not often seen, but you might look for gels that have a higher concentration of sodium or use an energy drink in place of water for most of your hydration.

On top of my serious addiction for Espresso Love flavored GU, I've also developed a habit of hording salt packets.  I make sure I always have a few packets in my hydration belt at all times.

Salt packets but with sugar (candy, gu,etc.) Your transporters need sugar to absorb salt. you'll notice if you take both at once.  Other things like energy drinks have electrolytes in it but if you really really need salt.  salt packets are perfect. But disgusting. 

Med student and marathon runner,

Caitlyn

Ken, congrats on the weight loss.  That's a huge achievement.  You mentioned "mistakes" you made last year.  Do you care to elaborate?

The physical effects of long distance training can vary greatly among athletes.  It's great to hear what others have done, but the key is to find what works for you.  This is why you need to experiment in your training and then stick with what works for your event.  Sports drinks, salt packets/tablets, and gels with electrolytes are all good sources, but some of my athletes prefer pretzels, potato chips, or other salty foods.  Your body does need a balance of electrolytes (sodium, potassium, calcium, magnesium, and a few other -iums) for optimal performance.

One of the main causes of hyponatremia is drinking only water, and not ingesting any electrolytes.  Pre-race diet, weather conditions, fitness level, and metabolism are also contributors.  I have known runners who have followed a good taper and pre-race diet who ran great marathons on a basic amount of sports drink and water during the race.  But, this is something they learned through their training.  When your workouts stretch past the 2 hour mark, you should start to really see the effects of things like electrolytes on your performance.  It's at this point that I start my athletes experimenting with things like salt packets to see how it affects their performance.  While all of my athletes are using sports drinks and trying gels that may contain sodium, for our longer workouts I start by recommending a salt packet every 90 minutes.  Once they get a feel for how they respond to various electrolyte sources, they can make adjustments to match their needs.

Keep up the great work.  Go Team!

I haven't really done any serious workouts in years, so hynoatremia hasn't been a problem and I combat mere dehydration by guzzling water.  However, ten years ago when I did workout hard and often, I would sweat like a pig in a slaughterhouse.

I can only go by my past experience.  I used to cut gatorade 50/50 with water and fill up my bottles with that instead of just water.  I found that mix to have just enough sodium to keep my fluid retention at the right level without having to pee every mile.