It would be nice if Wicket provided Ajax buttons to be used for the wizard component, see attached suggestion.
The attached patch does not work properly when on the last page was validation error. On such error, the default button will be the Back button and not the Finish button, so you couldn't submit the form with 'Enter'.
The suggested patch should be updated to Wicket 6/7 and applied.
AjaxWizardButtonBar offers ajaxified buttons now