Ya I thought about that but it kind of defeats why I wanted to use pages. Which is mostly to make it easy to understand and update for non technical users.
The following tables list the phases of Cloudflare products powered by the Ruleset Engine, in the order those phases are executed. Some products such as the Cloudflare Web Application Firewall have more than one associated phase.
actual cache runs at the very end though, if the question is "can I use rules to modify what normal cache uses" pretty sure all of them work, transform headers at least def does