[Tishabet]

Regarding bonking, I typically train up for centuries and do a few every season. I have found that I do need to fuel regularly in order not to bonk around mile 60, and for me the important thing is to consume calories pretty regularly and to have some variety so that I don't get sick of whatever it is I'm trying to cram down. I do not love eating much "real" food (sandwiches and stuff like that) during the ride, only before and after.

Here is what I use:
One bottle with plain water (maybe some hammer tabs or Nuun if it is very hot) and one with tailwind. Tailwind is great stuff, someone here on pelican first recommended it to me and it is great.
In the bento box: a few gels, some stinger waffles
In my jersey: shot blocks
Under my shorts leg: wrappers from all of the above
Note that some of these products (gels, blocks) can come with added caffeine. Ymmv but for me I have to watch the total intake on those or I will start to feel pretty gross.

One other thing to note: you mention that you are looking into getting a bike computer, so I assume you don't use one today. Getting a computer (or even just your phone with Bluetooth) and a pulse meter can really help you avoid the bonk and general exhaustion, and it is a great training tool. I find that "hitting the rev limiter" on my heart rate really takes it out of me, and I have my computer (in my case a Wahoo elemnt) set up to give me visual cues on what band of heart rate I am in. If I stay close to a certain sweet spot for bpm and drink enough water with just a little fueling, I can go for days and days.