Raised bed around a tree, oh my!

I have a problem with the large palm tree in the corner of the back garden at the end of the hopefully soon to be renamed, "Great Brown Way."    This year when I moved here that area, and all other areas, were coated in magnolia leaves.  This had the unfortunate effect of killing everything that ever lived back there, but it had an unintended positive effect: it stopped the soil from eroding.

When I took away the leaves what I had was just soil.  Nothing to cover it, and nothing planted to keep the soil put.  These facts combined with the rainiest winter season on record left the entire left hand side of my palm tree with roots hanging out all over the place.   Did I mention all the water from the neighbors hated garage drains there?

For the past month or so I have been puzzling about what to do about this.   I threw a bagful of topsoil over it, and that worked for approximately 3 days until it rained 2 inches.    I thought maybe lots of pots under there, but that didn't solve the problem that half the roots were already hanging in the breeze.   So finally my minds eye pictured a tiny raised bed around the area that would maintain the soil better and would provide enough room to plant some things so the soil was still there a few months from now.

I typed this idea into the computer, and up flashed a neon red sign "TREE MURDERER."  hmmmm.  Would this kill my tree?   Would doing nothing kill my tree?  I mean, palm tree roots are not supposed to be outside the ground in my experience.  Aside from that, one small hurricane and that tree with no soil on the roots stands a high chance of falling on my car.  Which would not be a happy thing.   I did a little more digging.  A few posts said, oh its fine: I raised a bed 18" inches 20 years ago and look at this beautiful tree.

Confused I went to the tree nursery and asked.  For those of you who have ever wondered, this is what he said:  You can raise a bed around a tree if you do the following:
1) keep it as shallow as possible, preferably 6 inches or less
2) do not encircle the entire tree.  Keep to 50% or less
3) keep the new soil off of the trunk of the tree.  This causes rot, the biggest issue with the entire process.

I can do that.   (half a day pause) I just did that.

I need a few more bags of soil to fill in the ends a bit, and an extra block or two, but aside from that,  I'm done.   That was a job.  But planting that elephant ear took approximately 4 seconds.