Not trying to spread grief here, just taking a cold, hard look at how I see Murphy's Law intersecting with IFR flying in a GA cockpit.
Foreflight = iPad dependent. It's a great tool when it works. However, that equals battery dependent, not overheated dependent, and external GPS source dependent (= wifi or BT dependent). The iPad internal GPS (cellular models) works OK when it works, but I've seen it break lock many, many times under totally benign conditions. If you're OK carrying up to date paper enroute charts, paper approach charts, paper airport facility directories, etc., as backup, you're good to go.
"But I've got Foreflight on my phone as a backup!" Yea, right. Can you really read the info on a low enroute IFR chart on your phone? Do you REALLY want to have to shoot an approach with the only approach chart available on a screen the size of your phone's? At night? Bouncing around inside a cloud? IMHO Foreflight charts on a phone serve the same purpose as Dumbo's feather (you young'uns can Google that one).
Carrying a second iPad that you keep current and charged with the same care you give your primary works as long as the environmental (heat) situation is accounted for. The thing is, you can buy a fair number of SA yearly subscriptions for the cost of a reasonably current model iPad and the SA data displays fine. The data integrates with Skyview seamlessly, and all your data eggs aren't in one technological basket. Also, if you buy your IFR navigator's data from Jeppesen, you don't need to spent the money for the Jep approach charts.
Just my $0.02 worth. YMMV.