RE: Looking for small 11.1V lipo packs
If you want a low "C" rated 3S Lipo, the best bet would be to look at the ones that are sold to replace an 8 cell transmitter battery, but most would be a little higher capacity. When you say you want one that's 60mm, do mean 60mm in its largest dimension, as in the length of the pack? I doubt that you'll find one that small in length.
Pete