Scanno, I am interested in your solution. Would you please elaborate a little by giving some practical details, i.e. how to create and switch easily from one user to another, etc. ? I'm using Note II, Android 4.3 - and Galaxy Tab 3, android 4.2, all with official rom and stock applications
Well multiple users is a default feature since jellybean. However it has to be enabled by the rom builder by setting a device overlay value. So I do not know if your roms have the multi user feature.
If you do have the feature, you will see an "Users" option in the standard settings app. You can create a new user there. Starting with kitkat (android 4.4) you have the choice between two types of users, a "regular" user that has a complete environment available or a restricted user. A restricted user can only run the apps that you give access to. Such a user does not have Play Store access.
Each user will have a separate data area and can have a pin code / password protection enabled.
Switching users is easy. For each user there will be an icon with name visable on the lockscreen. Pressing the icon of the user will switch to that users lockscreen.
Works fine with aqua mail.