Temp Tables

When using a temp table in plpgsql functions that has columns comprised
from many tables populated by joins, how do you specify a temp table return
type? I get an error when I specify returns setof temp_table. Also when I
specify a permanent table as the return type, I get extra blank columns in
the result set which are the additional columns of the permanent table I
don't need and the data is displayed in the wrong columns.

I tried defining composite types, but get a runtime error that it isn't
available.

Any help would be greatly appreciated.

Thanks,

Brandon