Avoiding the cramping that derailed my 1st marathon.

After years of being denied I finally signed up to run the NYC marathon in the fall with a charity. This will be my 2nd marathon, and I'd like to improve upon and avoid the mistakes of my first. Would love to hear thoughts about it.

Hartford 2021, was 41yrs old, I'll be 46 for NYC. Used the novice 18 wk Hal Higdon training program, intend to do the same for this one. I'm heavy (230lbs 5'7" and slow, my goal was 5hrs but it took me 5:45 because I had absolutely devastating cramping in my legs beginning at mile 16 that I did not have in any of my training, even at the 20 miler.

What I know went wrong. Lack of sleep. I slept like crap, I was in a new city. The marathon was switched from the one I was supposed to run due to covid, and it slightly altered the training plan to a slightly abbreviated taper. I powered through the last 10 miles doing some combo of running and walking as my body allowed. I felt good overall, but the cramping when it hit nearly put me on the ground.

I used GU, and clif bloks, though 5 years on I can't recall how much.

I'm going to be running this one with my wife, it will be her first. My goals are to get her to the end, but we both share a goal of our finish being 5hrs. I carried a hydro vest for that first one because covid, but for this one I can't carry one, and will use the water stations along the way.

So, for the other clydesdales out there, what's worked for you?

Happy to share any stats or data if that is helpful, but my best half marathon was 2:17:57, but best mile is like 9 minutes and it is insanely fast for me, best 10K is like 1:03. Looking ahead to the fall training I have 2 halves this Spring, I've probably done like 20 of those.

TL:DR, heavier, slower, middle-aged dude crashed at 16 miles due to cramping on first marathon, hope to avoid that on the 2nd. Looking for any and all advice.