I'm not sure if this has been developed. If not, anyone who is good at creating mods can take this and become famous.
Here's the idea:
Similar to ability range mod.
If we could make a jungle range mod.
It would give a range needed for the creeps to be outside of in order to successfully stack creeps. The circle would also be green from :00-:10 seconds and :30-:40 seconds. Indicating that if you kill the creep while the circle is green, the body will despawn allowing the next creep wave to spawn at the end of that 30 second interval.
first: the areas you're talking about are not round, they're angular
second: not possible
I think that the area is quite random. I've tried already to measure it, and failed completly.
I'm sure it isn't 500 range.
This isn't possible as I believe S2 uses regions to check whether or not there are units/corpses present in the area around the neutral spawns. It's not possible to add range indicators to regions as far as I know.