Thank you, Ovid. That helps me position myself, and it clarifies my feelings about the issue the OP raised.
Our code base for this particular project runs in the 90K lines. If I'm generous, I can take 30K off to account for dead code and unrefactored duplication. My feeling was that it's not exactly huge, but not trivial either. Your examples seem to corroborate that.
So, if two fairly competent, mildly disciplined coders can comfortably maintain a code base of that size, it seems entirely reasonable to me to suggest that Perl is quite suitable for big projects. Perl doesn't make it particularly hard to write modularised, well contained code. I don't see why it wouldn't be possible to create huge projects in it that way.