From my understanding, it is not THIS particular phone that is important at all, what IS important is the FBI setting a precedent to use for all future, similar cases. They care not a whit what is on this phone, they care about setting themselves up to access anyones phone at any time based on the rulings they hope they get.

I would suggest installing Deep Freeze Have it unfrozen when you yourself are using it. Freeze it before your guest uses it, Then one simple reboot and every single thing is back to how it was when it was frozen. Then just unfreeze for you to continue using it as a normal computer. We use this program on our WiFi Cafe computers after getting very tired of having to 'repair' the software about once a fortnight to clear various plug-ins, add-ons, programs etc that the users were installing. With Deep Freeze we have just set all the options as we need, then freeze it. No cookies left, no temp internet files, any virus or installed programs or anything is obliterated on reboot. Works great.