Better harvesting a bit too early than a bit too late. You may lose a bit in final bulb size, but too much delay results in bulbs that fall apart and do not keep as well.

Could be leek moth larvae (from Europe, I think - acrolepiopsis assectella - different from allium leaf miner which is a fly larvae)...along with the white rot on the plot, alliums are just a memory for me now. Astonishingly, I can manage to grow non bulbing spring onions and a decent crop of leeks as long as I use a specific resistant F1 variety - 'Oarsman'.

Garlic isn't bothered by hot weather, the issue with hardneck varieties (suitable for our area) is that they require a period of chilling to make a good bulb, and you may not get one. That said, a single garlic plant takes little space (and even less care), and you can sample a delicious scape, and can even eat the greens.

Try storing them in paper bags once they have cured and store those as close to the floor as you can - it is cooler there and in the dark if possible. That might help you retain enough moisture. I store my music in my kitchen in both mesh and paper after quite a long stay to cure on my front screen porch which gets pretty warm in the summer. I think you will also find that not all cloves dehydrate at the same rate. If some are starting to dry out, others may still be plump (I find this in my other hardnecks as late as early in the new year) and even when starting to dry out most cloves will still grow.