As yet I have felt no heat from the motors, though the frame bag with battery and controllers gets quite warm!! I haven't really given the motors a proper beating yet, as riding with Sarah needs patience when doing an average speed of about 8mph
. the one cool thing about these light weight motors is that I've found myself over the last two days off-roading, which I would not do with the weight of a big direct drive wheel.
Never mind fibre glass, what about carbon! - Phwooar!
I've never used fibre glass, but I bet you could mould some very user friendly cases or battery packs, it's a very interesting idea.
How's about
BMS's for your packs? Do they exist as components which can be bought?