Well, part of the answer might be this:

my $simple = XML::Simple->new(
                              KeepRoot=>1,  #I usually keep the root.
                              KeyAttr=>[], #do not use attributes as h
+ash keys
                              ForceArray => 1 #force array wrapping to
+ keep order
                             );
[download]

But I'm not sure you can have you're cake and eat it too on the criteria that:

print "2", Dumper( $tree->{project}{'PlayGround'} ) ;    # want this
+ all the time.
[download]

Anytime you want to reference something through the hash, you're giving up your ability to predictably order them.

Also note that I put these attributes on the XML::Simple instantiation rather than on the XMLin call. I would recommend you put this XML::Simple instance in the main and pass a reference to it to the xml1 function.