All b2Body uses 32-bytes for their debug name. Maybe this can be debug only?
I don't use the Box2D body name as I can use user-data to give it context but it uses 32-bytes so I've essentially removed it with some defines.
Would it be worthwhile adding in some define to remove it if not used?
I could use a string pool and make it 4 bytes. Are you concerned about some memory constrained devices?
I've found body names to be useful with debug draw and debugging in general. I've even setup a natvis to show them for a b2BodyId.
If I was concerned about memory I would have something like B2_SHIPPING that would remove names and remove debug draw code.
Also the place where the name is stored is fairly cold and doesn't affect performance much.