Seeing the asi from the back was never that big a deal,you can see it from the back. Anyway the citabria was pretty good at letting you know how fast you were going by feel ( and sound and smell and attitude). If you can't tell how fast you are going with your eyes closed do you have enough experience to instruct.
My biggest fear was that 'they controlled the mixture'. Followed up by 'they controlled the radio'.
On top of all that it was never that brilliant an aircraft. A chippy or a bulldog or slingsby gives similar perf without all of your worries.