Good Morning, Dave,
Apparently, the screen inserts used in smooth tubes don't cause any particular scratching problem as long as the film is loaded and unloaded carefully. Their only pupose is to allow solution to reach the base side of the film so that any anti-halation coating will be removed.
A simpler approach, and almost as cheap, is to acquire a color processing drum (I favor the Chromega, but Unicolors are used by many); these drums ordinarily come with separators and spacers to allow multiple sheets of film to be handled at the same time. Very small internal ribs keep the film from sticking to the inside of the drums and allow solution to reach the base side.
There are a lot of APUG posts on this topic; do a Forum search.
Konical