>> plant shallow rooted, heat tolerant plants there.
That's smart - use it for what it is, instead of working hard to try to make it something it isn't.
>> the soil outside of the bed. That is the native house pad soil of tightly compressed rocks and clay/silt. It drains perfectly.
I had forgotten, or didn't understand, that even the compressed soil drains well, straight down. I thought it was impervious, to throw water away from the foundation. You have no need at all for a "horizontal French Drain".
