.... I don't want to dose too much, because that can interfere with normal plant growth,
We never have "normal plant growth". We try to get healthy growth at the rate the light is driving the plants to grow.
just like too much light can burn out a plant.
I have never heard of so much light so that it will "burn out a plant". More light makes the plants grow faster, as long as there are sufficient amounts of all of the needed nutrients available to support that growth rate. With less than sufficient amounts of any nutrients, and a mix of plants in the tank, the more aggressive growers may hog the nutrients, causing the less competitive plants to suffer, and causing algae to start.
The excess ferts would likely be wasted when I did my weekly water change.
Fertilizers are cheap, so wasting them isn't an economic problem. If you use the drained water for outdoor plants or indoor container plants, you waste none of the fertilizers.
I'm sure you know this stuff, you may just be testing me.
I'm not testing anyone, just trying to post what I believe to be facts, along with my opinions.