How to prevent keychain passwords being seen with iPhone passcode? Via Settings/Safari/Saved Passwords/ it is possible to view all saved passwords by simply entering the 4 digit passcode on ones iPhone.

Is it possible to still be able to use Keychain passwords and autofill, but prevent access by the 4 digit code (e.g. requiring the full Keychain/iCloud password), so that someone who knows your phone code is not able to access all of your internet passwords in plain text?

EDIT: it is possible to set a different 4 digit code as the "Keychain pin" via turning on Settings/iCloud/Keychain/Advanced/"Approve with Security Code", but the phone 4 digit code is still used for accessing the saved Safari passwords as above... It would be great if there was a way to always require the "Keychain pin" instead.

RELATED: the analogous problem on Mac OS X: How to prevent Safari saved passwords being seen with Mac password?.
I hate to reference unreleased software, but quite frankly the solution may be for you to enroll now in the iOS 9 public beta or simply wait for it's official Fall release. iOS 9 (at least in its current state) gives the option to set a custom alphanumeric password in place of the familiar 4-digit pin. 

So, if you have hardware with touch ID capability you could use that for your everyday login and reserve a more complex passcode (even the same as your iCloud one, like you mention) for protecting your keychain in case of theft, etc.