Customer Edits for Requsitions

Using PeopleTools 8.61, FS/SCM 9.2 (latest PUM)

TLDR: what's the best supported way for applying customer edits to a Requisition submission?

We have a large number of edits/rules to apply to requisitions before the requisition is submitted for approval.

Fluid Requisitions aren't really built for applying normal Event Mapping customizations - it's a complicated wrapper with fluid pages that don't trigger Save Edits, interacts w/ a synchronous Requisition CI - the data is sometimes in a global cart object, sometimes in the component's buffer, sometimes in the underlying CI. You can add Event Mapping to the underlying CI at save time and that works fine, but it's kind of kludge and seems ill advised. What's the best design for applying the edits so that they're applied before submission? I tinkered w/ using related content, the UI design is so