If I understand you correctly, you have an add (or update) form and you want to see what those fields would look like in a preview display (like a paper form equivalent). I would use an add/update form to input the data fields. At the bottom have 2 buttons:
one would do the add/update without preview and one would show the preview display. The fields could be sent over in context or even stored in a temp row of a holding table. Then, on the preview page, you format the preview appropriately. You could have 2
buttons: one to accomplish the update as is and one to return to the previous page so changes could be made. With all this, you stay within Django and maintenance is simplistic, too.
Hope I understood your situation. If not, just ignore this.