There was an old topic a while ago in the lounge about water-bombing, which sadly has not been posted in for quite a while. I thought it was a good idea, so here's a request with my ideas of how it could be done. These may be completely infeasible, but there's no harm in airing my thoughts.
First, a loadout for the A-20 / Boston that consists of many (hundreds) of munitions that appear as a simple 2D (or a few 2D shapes arranged in 3D) splash of water (some sort of generic spray texture). These would drop one after another, quickly, with a single press of the release key, and could just be carried in the bomb bay. There's a weapon like this on some versions of the IL-2 but I can't remember what it's called. Each of these sub-munitions would only do a tiny amount of damage. I'm sure some of the skinners around here could make a nice fire-fighter skin for the Boston. If one wanted to add complexity to this idea, the water "bombs" could have a new explosion effect that looks like water splashing on the ground.
Next we need fire. One of the already placable fire objects could (maybe) be modified to move like a vehicle (very slowly). It would be very weak and easy to destroy with the water "Bombs". It would also have a very short range, invisible "gun" that can destroy another new object, a tree or group of trees that when destroyed turn into charred trunks (possibly with a light smoke effect). The fire would be set up in the mission as red and the plane and trees blue (or vice versa) so that the fire "attacks" the trees as it passes. Add to this a few static objects to create the impression of scorched ground that can be placed behind where the fire object starts and there you go.
This could also work without the moving fire front to save complexity as it wouldn't have to destroy any new trees, just sit there and get put out.
Burning buildings could also be simulated with the same idea of making them very weak and susceptible to the water.
I have no clue how to do this, and no access to 3D modelling software unfortunately, but if anyone were to take this on I'd be glad to help in whatever way I could.