How can I implement a transaction of 50 writes in dynamoDB?

Question

I’m aware there is a hard limit of 25 items per transaction. However, I’m sure there is a way of implementing transactions for more items from scratch. How might I go about it?

I’m thinking something like, keep a version number on every item. Fetch all the items up front, during insert verify version number is the same. Ie optimistic locking. If the condition fails, revert all failed items. Naturally, I can imagine that the revert could fail and I need to do optimistic locking on the revert and end up in a deadlock of reverts.