As you are an adult and there are no Whole30 police, you can do what you feel is best for your body, understanding that should you have yogurt, you would not have completed a Whole30 as dairy is not compatible with the program. With a quick google of 'Anti Candida Diet' I got a list of principles that ARE compatible with the Whole30 including eating fermented foods (kimchi, saurekraut), low sugar fruits, mostly non starchy veg and minimizing caffeine.
See if you can spend some time researching other things that are recommended for anti candida that also fit into the rules of the Whole30.
Sweet potatoes are definitely out on an anti-Candida diet. Personally if I were aware my main issue is candida overgrowth, I would do the candida diet, rather than W30 (or after- but doing them at the same time would be very limiting). Disclaimer- I am not an expert, just someone curious about this subject and working on it for myself. The two diets are similar in eliminating all added sugars, bread, white rice, and most dairy. However candida diet allows plain yogurt (probiotic), butter, and pseudo-grains like millet and quinoa, while eliminating most fruits and starchy veggies like potatoes- it's all about eliminating what feeds the overgrowth. There are also various stages of the candida diet, starting more strict then gradually allowing more fruits, etc. I haven't tried it personally but am trying whole 30 instead for now, since my symptoms aren't clearly a candida issue, but I'm considering trying candida diet next, as a comparison. Layering both diets at once, like you said, might result in an overly limited diet without enough options to stay fed, I would think.
By the way, congrats on doing ANY kind of no-sugar diet, coming from serious sugar addiction! That's gotta be a rough transition. I'm about a year and half into a no refined sugar rule, (with Nov/Dec holiday exceptions), and it's the best decision I've made for my diet. It's easy enough to follow, especially when I allow natural sweeteners like honey, and it keeps me away from all the candies and donuts, impulsive food choices and processed foods with added sugar. It's the world's simplest diet and makes a big difference.