Custom 500 Error Page / Radiant on Dreamhost

[csvy]

I'm running the latest RadiantCMS on dreamhost with passenger, which
is a complete disaster. Even with no extensions installed, the site
constantly gets "The application spawner server exited unexpectedly"
along with a big trace. Dreamhost Support claims that we are using
too much memory and that we can't use shared hosting because rails and
radiant are memory hogs (although we had no memory issues with FCGI -
although there was an issue with Radiant where the multiple
dispatch.fcgi's would sometimes write to the cache at the same time
and crash the app for like 15 minutes, so we really can't go back).
What I'm wondering is whether 1. anyone knows why this could be
happening, since it really doesn't make sense, or 2. does anyone know
how to customize the passenger 500 error, so it doesn't show a full
stack trace, and can instead show a helpful error message to the user,
like "sorry for the delay, please refresh" or even do something tricky
like 'you have been randomly selected to participate in a user survey,
click here to accept, and here to refuse', which could be a static
page pointing to a dynamic page, and the user wouldn't realize
something had gone wrong. Thanks