A Body filter after postpone filter

[Sirsiwal, Umesh]

Hello,
I am trying to develop a filter that encrypts payload. For our application, SSL is not required. Because of the actual payload can be assembled using multiple asynchronous upstream calls, the filter must be applied between after postpone filter. It can be before or after gzip filter because we really don't use gzip filter. Based on my reading so far, there does not seem to be any way to achieve it without patching auto/modules file. 

Is my understanding correct or is there a cleaner way to achieve it?

-Umesh