Had a shocking 20% RH today when I came to the crime scene.
Nobody was hurt at this point, so I went on with my duties...
Cooked myself a pot of spaghetti, that got the room back up to 35% RH, but it would go back down very quickly.
I tested my own idea and set up a drying rack for clothes with a huge towel that I had thoroughly saturated with water near the heater/window.
Also put a tiny bit of water in 2/3 of the coasters and voila: 50% RH close to the pots 41% RH above my canopy and at the intake of the tent 36%.
Gotta give a shoutout to my dad, he actually came up with the idea of the towels on a drying rack with their tips in a waterbucket in front of a fan.