I take a similar approach to you, and am also a solo dev. I would take a serious look at client-side frameworks if I was building something more appy than websity. It might also make more sense if I was working with others and there were separate front end and back end people so defining some kind of back/front end interface would make sense.

With regard to the admin, my experience is that usually the customer will have specific tasks that they need a workflow for, and the admin panel is often not a good fit for that (and things get messy quickly if you try to bend the admin panel to be something it isn't).