Kjarl Thotep, smeerp-friend, lacks our dimension's cultural concepts of personal space.
Why does he think Tarvek, of all the party, is insane?
Setting aside the magnificent coiffure, I'd put his height at about 7 feet. Gil comes about to his chin.
Also, anyone who can hold Tarvek casually in one hand does not lack for physical strength. I'd say Tarvek's a little fellow, but still probably weighs 130 pounds.
EDIT: unless I'm missing something with my aging eyes, he always has 4 fingers and a thumb on each hand. Thumbs are not always visible but I believe in object permanence.
Also, I wonder what the Sparky powers of his monocle will turn out to be.