But I don't see how cover channels can even work as you describe them? Where does the constant flow originate in onion routing?
My idea is that the cover traffic channels would be the outermost layer for communication between nodes participating in the mix network. You perform routing and onion routing through these channels.
Afaics, there can't be a layer outside the onion routing maintaining constant flow to outputs of the network unless you have masternodes in control of maintaining the constant flow, which would then be egregiously vulnerable to Sybil attack. How do you envision it working otherwise?
Thus constant flow is inimical to the obfuscation of fixed points through autonomous randomization (increasing entropy), which makes a Chaum
mix-net work.
Tangentially: the beauty of one-time ring signatures if they are creationally autonomous thus entropy increasing. Entropy increasing designs are congruent with the
universal trend of nature (because mutually observable space-time is irreversible). Unfortunately one-time ring signatures are also collectively bound for destruction, i.e. kills pruning.