This got bounced the first time.
 
If you do decide to move the get-together from the main bar, could you leave
a note or something for us late arrivals (I have a meeting until at least 5
PM) so that we can find you.  Is the main bar (bars?) too noisy to talk?
 
And yes, you can lay tile on wet earth or mud, and the tiles will bed nicely,
but once the ground dries out there will be a greater tendency for them to
break.  This might be worthwhile if there will be no heavy traffic, such as
indoors; you want to keep initial costs down; or you don't know any better.
 
If you waited for water to drain between tiles and then through a bed
of compacted sand, you would still end up with a damp floor unless there was
sufficient pitch (of the surface and the underlying prepared ground surface)
for the water to drain.  With a sufficient pitch the water will drain much
more quickly off the surface than through the sand below the tiles. Sand
would keep the wet clay from oozing up between the tiles, though.
 
I have an idea, why not ask some recent arrivals from Mexico in the
construction trades about it?  Asking archaeologists is like asking doctors
how to build a bridge.
 
Tom Wheaton