Since planes don't come around too often (except for lazy tankers asking for spotting), how about moving the spawn points to behind a thick forest, not really possible with the single vertical trees of now, but if there were top and front (facing the view from the town to the spawn points) semi transparent sprites like Nuttz and others have made.
This way there is cover from above for planes, and a bit less (in density) from around for tanks coming to camp. There is enough around, you're not completely blind, but a camper would be as much a sitting duck to tanks spawning around him: there is only enough visibility to see point blank range, not enough to effectively plug five spawning tanks at a time.
Ideally there is more elevation variation within the spawn>town forest zone so you don't have to rely on too many tree cover sprites, but that's maybe not possible with the TE as it is, maybe put indestructible structures instead in a ring around the actual tanker town; of course not in a simple disposition that makes it easy to snipe across, but dispersed at random like the inside of the town.
so a balance between covering sprites and 3d structures and giving less interest to the path of least resistance of going out of one's way to go spawn camp.
