Better too loose than too tight.
A setting of 0.05mm is not really possible but to get the measurement between 0.05 and 0.1 is what you ideally should achieve. If the box is back together and the biggest gap is not more than 0.15mm I would leave it. A larger gap will most probably have a bigger influence on the shifting quality than bearing wear as the shafts can now migrate more freely forward and back.
Have you added the gasket thickness in your calculation?
I have found gearboxes with the end-float of over 0.3mm with no obvious damage caused by this but if even just slightly preloaded the bearings will start to wear excessive within the first 1000km.

Exploding gearboxes is not that dramatic but it does wreck havoc with the insides, shafts and gears, and almost always damages the gearbox cover. Repairs can be astronomical, so it is safer to have the gearbox overhauled before this appears. Check for metal filings on the magnetic pickup on the sump plug. Fine fibers that leaves your fingers dark grey and feels silky when you rub it between your fingers is normal but if you see and feel shiny flakes when rubbing the material on the magnetic plug between your fingers you can be assured that a bearing is on its way and it will be safe to say you should have it attended to in the near future.
You can also get a clear indication by turning the back wheel when on the centre stand and the motor switched of. A nasty rumbling noise that progressively gets worse when checked regularly is also a sure sign that the bearings is busy failing. Just make sure this rumbling is not part of the final drive which will mean you might have to service that instead.