I'd say: Every module you use should include a use VERSION ° for the minimal version needed.

So descending and checking one level should give you the needed versions and you have to require the upper bound.

Of course this requires that all those modules already did their "homework" by checking one level deeper, etc...

If you want to automate this, maybe consider an @INC hook which is parsing all required modules for VERSIONs before evaluating them and emitting the max version found after compilation was done.

UPDATE

°) actually require VERSION is the cleaner approach for exactly this semantic, because it doesn't also activate features like use VERSION does