Plain water between a few feeds? Smaller doses? (To prevent nutrient burn)

it's not easy to evaluate how much water evaporates, leaving nutrients in the soil, and that's the problem you're referring to. normally, when it's too hot, water evaporates very quickly, so frequent watering with just water is right and necessary, but in boxes with lower temperatures, evaporation will be less, so watering with just water should still be done but less frequently... and anyway, the plants talk to you, you need to be able to understand them and you'll see significant improvements... even if you're already doing a great job like this.