"Cast" SRF returning record to a table type?

I'm working on a function that will return a set of test data, for unit
testing database stuff. It does a few things, but ultimately returns
SETOF record that's essentially:

RETURN QUERY EXECUTE 'SELECT * FROM ' || table_name;

Because it's always going to return a real relation, I'd like to be able
to the equivalent of:

SELECT ... FROM my_function( 'some_table' )::some_table;

Is there any trick that would allow that to work? I know that instead of
'SELECT * ...' I can do 'SELECT row(t.*) FROM ' || table_name || ' AS t'
and then do

SELECT ... FROM my_function( 'some_table' ) AS data( d some_table )

but I'm hoping to avoid the extra level of indirection.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com