Nutrition and caffeine during a 10 h skimo race

Hi fellow uphill athletes,

looking for your advice regarding fueling during a 10 h skimo race.

Duration is fixed, the goal is to gain as much vertical meters (and downhill) as possible during the 10 h time limit.

Last year i managed to get in about 60-70 g carbohydrates per hour consistin of 30 g in drinks and 30-40 g with energy bars.
In the summer of 2023 i did an more intense race over 6h were i was able to consume about 100 g carbs per hour with the mentioned fuel sources and an addional gel every our. In both race i had zero problems with my stomach.

I plan to do an “test race” about 4…5 weeks before the actual race to test the fueling strategy (100 g carbs/h) with “race pace” over a 5 h skimo training session.

FIRST QUESTION:
If i have no problems with 100 g per hour – should i plan for this amount for the 10 h race? Could this be to much carbs for a Z2-(Z3) effort?

I am planning to expand my supply strategy to include caffeion, but there are a few questions arises.
So far I have found that about 3 mg per kg of body weight is the optimum between effect and risk of side effects. Furthermore, the half-life should be between 5…7 hours in the body.

The benefits are higher fat oxidation, pain suppression, less fatigue and improved coordination and therefore more efficient, energy saving (carbs saving) movement.

SECOND QUESTION:
What would the better strategy:

Case A) Caffeine from the start with regular top-ups?

Case B) After about 5h?

Looking forward to answers and a discussion!