I used to have similar issues with the bars/gels combo during ultras. Using more liquid calories helped quite a lot. It's maybe worth trying it (either something like Maurten 320 powder or, recently, I started mixing my own with pure maltodextrin, fructose, and electrolytes mix). Anyway, good luck with the race, Marco!
Have you tried fully liquid nutrition?
I would not have an athlete with your profile race with solids or gels.
The uphill start for the ultra... Do you have a strategy for dropping HR down so the body continues to process liquid calories?
I used to have similar issues with the bars/gels combo during ultras. Using more liquid calories helped quite a lot. It's maybe worth trying it (either something like Maurten 320 powder or, recently, I started mixing my own with pure maltodextrin, fructose, and electrolytes mix). Anyway, good luck with the race, Marco!