I think doing the water water feed method is a good choice, fixing a deficiency is much easier than a toxicity. I'm a firm believer in less is more....usually. my outdoor grows have been a W, W, F schedule like yours and the only time i had a problem was when I misread the dose for calmag...and it completely caused a problem. I think most people's 1st solution to buildup is to flush, regardless of what you're gardening. But you can flush with an additive that helps breakdown salts like Sledgehammer by foxfarm, otherwise we can use organic materials like peat moss or compost to help neutralize the salts. . I wanna say even using good mycorrhizal fungi products help too...they'll either help consume the salts otherwise maybe make the roots stronger at resisting the salts, and they make nutrient uptake extremely more effective so you dont need as much nutrients to begin with.
This was a cool question. Happy growing. ✌️