What about adding a checklist function that is integral within SkyDemon iPad?

Well, ish. The great virtue of electronic checklists is that you can actually check items off - the 'done' function on the Foreflight app - and positively confirm that you've not missed anything. An electronic document is no better than a paper card in that respect. Considering how easy it must be to create a simple user-configurable checklist, and how universal its use would be, I'm surprised such a comprehensive tool like Sky Demon has yet to follow most of its competitors and provide it.