I love this scene. There's so much to it, and it's so well organized.
I do really wish we could figure out a good way to pull off the dusty light shafts through the barn slats. I did some research on that and found a couple promising plugins:
Stopper's "[Experimental] Volumetric Global Illumination"
An initial attempt at importing SEGI global illumination into VAM. All credits go to SonicEther. https://github.com/sonicether/SEGI This project hasn't been updated in ages, so I doubt I'll get it to perform better than it currently does. The...
hub.virtamate.com
PluginIdea's "High Performance Volume Light"
Are you often troubled by the fact that VAM has no reliable volume light effect? Actually, VAM itself is already a game that consumes a lot of performance, while volume lighting is a frame-eating monster, especially when the number of lights in...
hub.virtamate.com
I found a scene that showcases PluginIdea's HPVL, but it looks to no longer be available as a resource on the hub: Natsume's "Nordic Snow Hut". Here's what that looks like:
Anyway, I inspected that scene and then recreated the effects within your scene. I ended up using both of these plugins in tandem, as Stopper's seems to have better global effects while PluginIdea's has a nice fog cone feature. I am still having trouble getting more than one of these fog cones to show up, for multiple slats in the wall, but it seems like it should be possible. Perhaps similar custom VFX assets could replicate that portion in a simpler and more flexible way.
Here are some example shots (the fog texture is animated, so it looks better live):
I can extract the lights with their plugins as a subscene for you if you'd like to play around with it. Regardless, I love this scene, and I'll keep working on this concept locally, but I really hope my information will make it possible for you to realize your initial ideas for this scene.