Just don't try to update the maps and other big datasets via your phone. That would have to be an EXTREMELY long pre-flight you're doing.
I bring my tablet(s) home and keep them updated that way. Like you, I sometimes forget them. (I try to find ways to reduce those occurrences, such as putting it/them back in my flight bag after updates.) But if I forget, my phone (with iFly on it) provides my backup. It's small, but it works OK in a pinch, and it's always up to date.. In fact, I've decided that will be my primary EFB in my amphib. Which...
...freed up a tablet holder to mount on the passenger side of my other airplane (I already have one on my side). Then I went on Craigslist, found an extremely cheap 8" tablet ($30), and that will, for the most part, remain in the plane on the passenger side. Gives them something to play with, and they can set it to whatever type of map display suits them. (And, obviously, provides a different map display for me if I want; and provides a backup EFB for me if my primary fails; and provides an EFB [if sometimes out of date] if I forget my primary tablet at home.)
P.S. If anyone else wants to score a low-cost tablet, I suggest you look for Playster tablets. They're 8" Android tablets that people get for free if they subscribe for 12 mo. to the Playster media service. But they're not "locked down" in any way, and will run any Android app, incl. iFly. For $30 I got a new one in the box that this person never used. Just a note: for some reason iFly does not recognize these as tablets, so you have to set it as such in Settings if you want it to provide better looking map and menus. That's a one-time thing -- unless you flip-flop back and forth between landscape and portrait (or vice versa). In that case, iFly keeps setting itself back to phone mode. It's a very minor annoyance, requiring five menu taps to rectify each time, and that's only if you switch back and forth between orientations. I'll report it.