Help with next year

As long as you use Boston as just a long supported training run and don't race it, you should be fine.

Looking at your race reports and logs, it appears that the reason your HIM was miserable may have to do with both hydration issues and lack of sufficient bike fitness. Work hard on the bike during the off season so it allows you to be strong starting the run. You obviously have some good talent and should easily knock more than 2 hours off your HIM time.  With improved bike fitness and the hydration issue solved you may even go sub 5 considering your running ability. That first HIM was more like an anomaly.

Thanks for taking the time to look at this in depth for me. Very sound advice given. I need to save this post and refer to it over the coming months.

A couple things - Your bike volume is way low. I'd consider it adequate for a sprint. You are doing only a couple hours a week, and I don't see hardly any workouts over an hour. You should at least occasionally have a long ride of race distance, and a lot more workouts in the 90-120 minute range.

Running looks fine, and as the above guy said, treat Boston (Lucky you!!) like a long supported training run. High five the crowd, talk with people, etc. so that you don't get the urge to race it.

The other thing is your swimming volume. Again, not even what I would consider adequate for a sprint. At least 2 workouts a week in the 2-3000 yd range if you're considering a HIM.

So, you're undertrained in two events, the bike and the swim, so that by the time you get to the run, you've pretty much spent all the gas in the tank. If you don't get the volume up in the bike at the very least, the "anomaly" of your first crash will become a trend.

Over the next 5 months (through the end of Jan), I would concentrate on keeping the run volume up, and getting the bike volume up to double what you are doing on your run totals. (There's a few times your bike volume is less than your run volume. That should never be.) I'd be shooting for 25-35 on the run just like you're already doing per week, and a weekly bike volume of 60-150 (The larger end of the scale towards the end of your build period), with a long ride of 2-3 hours at your current pace as a goal.
 
Then once Jan is over, you can start working on adding strides, intervals, bike intervals and hills, etc. leading up to your April and May races.

For the swimming, if you need it, take the next 4 months and get some good instruction. If your form is ok, then work on getting the volume up in swimming as well. While the swim is a small portion of the event, you don't want to either come out so far behind you don't have a chance to be competitive, or so gassed that your bike/run fitness is compromised.

John