What's the best way to stow (winter storage) an all-carbon bike?
I don't see a problem hanging a bike from a carbon fiber composite rim. The amplitude of the load would be much, much lower than when riding over even moderate bumps. OK, the load is radially outward rather than radially inward but the wheel is not weak in that direction.
Maybe of the inside edge of the rim is particularly narrow in profile you could damage it, but suitable padding would prevent that.