I'm not sure whether I fully understand your problem. I am guessing wildly that part of your problem is that you are sharing installed modules between different platforms via NFS/SMB/...?

I am guessing that because your problems seem to be based not on features not available in a certain version, but rather your installation being a mess.

To achieve portability on that number of platforms, I'd go the following steps:

• On each platform, do a clean install of perl and the additional modules you need. That should make sure that core modules like e.g. IO::Handle work.
• Depending on your code, it is probably just a few of your own modules that behave differently on different perl versions. I would prefer to do the version checking inside those modules, for better abstraction.
• Make a bundle of your own application to facilitate deployment. Then, do a clean install on each platform.

Update: You could try to use PAR for easier application deployment.