I agree this is a difficult problem - especially in a flight school environment where the planes have high utilisation. The solution:- buy a different publishers book on the aircraft type (generally avaialble from Amazon.com) .
All critical parameters are in there and give a good idea of the planes performance. Whilst being aware it is important to have the very latest information onboard aircraft, on trainers etc have things in the document that are important to the safety of flight actually changed that much since the aircraft was first designed in the 1950's or '60s?