Shiny plastic no good for guerilla, but could paint it black…
There’s also those terra cotta vases you can put in the ground up to the neck, they slowly release the water through their porous walls. Saves a lot more water compared to watering onto the soil.
Companioncrops providing shade are our friends.
Always make sure no bare soil is visible anywhere, grass is great too as it has shallow roots and harvests dew, and makes it difficult for slugs.
I notice toads, frogs, lizards love tall grass, and they eat caterpilars and just about anything that is smaller than them.