I now have a solution that seems to work. I have extracted a minimal set of tests that demonstrate the problem and my solution, which I have attached as an archive (tar czf format).
I'm not completely happy with my solution, mostly because I'm notcompletely sure why it works -- or perhaps more to the point why it is necessary. I keep thinking that the mod_dir DirectoryIndex should "just work" but of course that's bootless. Either it doesn't in this situation or I don't understand something.
I'd be pleased to have a better solution. Or an explanation of whythis one works. I have tried to reduce the problem to the smallest possible footprint to make it easy to review, for them what has the time and interest.
Failing that, perhaps this IS a good solution and may benefit some other poor soul.
Marc M. Adkins
mod_perl_config.czf
Description: Binary data