Here's a post I put together about it: https://jasonc.me/blog/chained-0-conf-transactions-memo
It's not trivial, but it's still fairly easy. w/bookchain we split coins into however many utxo is needed. memo could change to switch between 3-4 diff "utxo chains" until nodes supprt
Edit: Oh wait, you already more or less do that, didn't read the full thread before replying. Should be split automatically though if users are complaining about it.
