or even if it would be feasible.
I fully understand your reluctance to use the max mounts for the reasons you quote. But similarly the reverse could be true if you only want to know the number of times a piece of media is filled - it could be mounted '000's of times & only filled to capacity once! So maybe you need to look at the amount of data written? But then again, depending on the type of data the amount actually written to tape could vary from a few hundred meg to over a terabyte!
May be someone else has, successfully, achieved what you require?