There's no distributed implementation of ripple. But you don't need a complete for two AH to trust each other.
They just have to be legally liable between them. Note that they don't need to be directly liable, a web of trust can be used.
For example, Payer has an account with AH1 and seller with AH2.
At the moment of the payment a message is sent to AH2 with the form:
Do you trust AH1?
If it's not in the AH2 list of trusted AH, he can ask the same question to the AH in his list and they (before answering) can ask other AHs too.
There's only the need for a path of trust from AH2 to AH1.
You can read an interesting document about the problems for distributing ripple here:https://groups.google.com/group/rippleusers/browse_thread/thread/acb472ad92e77d2c?hl=es
There's debate in ripple about how to adapt bitcoin technology to implement a distributed ripple. If it's done, maybe the time for ripple transaction verification doesn't fit with your protocol. Ryan has also an idea for real-time confirmation here:http://bitcointalk.org/index.php?topic=4382.msg64109#msg64109
I don't know if its feasible.