I think we're off the paint topic ?

I find that the fabric will flow around wing tips
and other tight areas better than a film.

The covering I use is dependent on the subject matter

My PA 18 is glass where the sheet metal is and fabric
every where else,my Spitfire is done in a similar fashion,
because the fillets are metal, I glass them. Trying to get
an iron on covering , (film or fabric) on fillets is a very
difficult task. I can't do it and make it look good and
I'd end up with a ton of seams.

Like I mentioned before, I am not a fan of iron
on films.

Get a "test plane" and go at it. It may cost a few bucks
but you'll learn a lot.

Roby