Thanks for the pic of the mirror Andy. It actually looks OK in place, at least for mine, as photos show it was rather large.
As for the IFF antenna - good one! It's a tricky period to model, as the post aerial was just starting to be fitted at the factory or MU, and was retrofitted later in the field, or in 'deep' servicing. Certainly by mid to late summer '43, the MkIII IFF was in use.
For future reference, if you need to make one for another model, it wasn't a whip aerial, but a tubular, aerofoil section 'post', around 12 to 16 inches long IRRC. (I can get the exact dimensions if you need them.)