Submitting patches and bug reports for modules via RT is the most important thing you can do, because others will be able to see your bug and patch there, no matter what the future fate of your contribution with the upstream module is.

One possible solution for you is to also maintain a set of Distroprefs for CPAN and offer them for download via CPAN. That way, people can directly incorporate your modifications to modules into their build of CPAN.

On the social side, please also see that an author does not always have the same priorities as you have, and if there is nothing to currently add to a bug report, a "thank you" note would surely be nice but is not always sent.

A module author will always be a "single point of failure", but if you don't want a single point of failure, you hire multiple backups. If you think you've found a way around this without paying people to work on code, I'm sure people will look forward to hearing your idea. Personally, I doubt that any technical scheme, like requiring "two maintainers" will work. This will just make people "swap" maintainerships and not be more responsive to your requests.