well, the height observation might not work since Tom was one of the tallest performers, so logically, Clara might have appeared to shrink from his POV. Unless, of course, the Baker-ish Doctor is either sitting or on his knees and is unaware of his stance.
Lance Parkin has a passage about height from the Doctor's perspective in The Dying Days
; the eighth Doctor asks Benny if she's changed her height when they meet.
The eighth Doctor is considered one of the "tall" Doctors, but McGann isn't any taller than Sylvester McCoy. But when the BBC did some promo shots, they had McGann standing on a box to make him look taller than McCoy.