I haven’t, and some people report noticeable increase in flatulence with more than 2,500 kcal/day from Huel. Not sure if that has to do with the sucralose in the Huel White, or something else may be affected by each persons’ physiology.
But the good news is your type of question is why I wrote the Custom Huel Kcal Calculator. You can use it to set your target body weight and kcal intake/day, then adjust the amounts (serving sizes) and timing of your meals (and what you eat). My calculator is preloaded with a few choice ancillary food items including pea protein, rolled oats, extra fiber, omega-3s and MCTs.
Considering you’re making a weight gainer I’d suggest swapping out the desiccated coconut for a plant or animal-based milk to boost your kcals without adding more solid food. All you would do, and this is true for swapping any food item in my calculator, is type in e.g., Oat Milk (it’s better for the Earth than water-hungry almond trees) in place of Desiccated Coconut and then input the milk’s carbs, fats, and protein (leave zero for fiber) in place of the Desiccated Coconut specs.
Then just adjust the severing sizes (grams) and timing and number of meals per day to meet your RDAs (e.g., for fat) and target kcal/day.