Wow - incredible work!
Question for you kit builders: Do you guys paint them while they're still on the trees, then trim and touch up? Or do you cut 'em off, then trim and paint?
I usually follow kit building in this order:
1. Snip out individual parts from the trees (as instructed by the manual).
2. Snip out the excess tree material that may remain on the parts.
3. Apply plastic cement, and attach parts together. Leave for 24 hours.
4. Sand out the whole part to a smooth finish, making sure to remove any dried smudges of plastic cement.
5. Spray primer (Tamiya). Leave for 6 hours.
7. Paint.
In my opinion, you should follow the steps that I listed if you want to turn your Gundam kit, into a sturdy Gundam action figure. The key, is applying either plastic cement, or super-glue to bond the parts together, before you paint. If you don't use some sort of chemical adhesive, then your finished Gundam kit will be flimsy and will tend to fall apart very easily.
Now, taking what I said into consideration, although spraying the trees directly will save time in the short run, I won't recommend it.