Display of actual values persisted for controls that are bound to http actions

We are currently using Orbeon Forms version 4.1.0.201304182144-PE. We have designed an Orbeon Form in the Form Builder which has several interrelated components which are bound to http actions:
-    Eligible year (drop down)
-    Eligible period (drop down)
-    Amount to pay (label)

The user fills in the components in the order highlighted above. The drop downs do not have default values as they are all data driven. We have wired together the HTTP actions using event changed. So after the user has selected an eligible year, we determine eligible periods for a year and so on.

What is the best way to display the data that the user has submitted? We do not want to make a HTTP call to determine the values when the form is re-displayed in read only mode. These calls will no longer be valid as eligibility is updated once a period is paid for.

The only way that we have thought about potentially resolving this issue is to use XPath expressions involving form runner modes (http://wiki.orbeon.com/forms/doc/user-guide/form-builder-user-guide/xpath-expressions#TOC-Scenario:-checking-the-Form-Runner-mode). HTTP actions might then only be invoked if we were in edit or new mode, whereas read-only might show labels for eligible years and eligible periods instead of drop down boxes. Is this the best approach or is there a better way of doing this?

Many thanks
Graham