I have just had a look in The Long Drag by Don Evans.
He confirms that there was some air to air firing with Sleeve type targets during WW1 - although he thinks that they must have been relatively small sleeves because of the 'performance' of the aircraft at that time.
He also confirms that there was little if any A2A firing before 1929/30 when Avro 504K did some banner towing,he also states that he saw a photo of a Blackburn Baffin towing a sleeve over Martlesham in 1931/32 (testing/trials work ?).
(Don Evans was a T.T.O during WW2 btw)
As to the 'Fighter Escort' subject,with the advent of long range bombers - (all the way) long range fighter escort became impossible anyway until the merlin P51 came along with its 485 US Gal fuel capacity.