It looks like a subset of classless qdiscs can be combined with each other in certain configurations. In fact it doesn't make sense to me that you could not do this, since things like codel will only work sanely if you can limit the outgoing bandwidths using another mechanism (eg a token bucket).
I cannot, however, find any sane documentation. Are there any good examples or writeups about combining classless qdiscs to achieve target rate-limiting and fairness behavior?