automount nfs: autofs timeout settings for unreliable servers – how to avoid hangup?

I’m running a small server for our flat share. It’s mostly a file server with some additional services. The clients are Linux machines (mostly Ubuntu, but some others Distros too) and some Mac(-Book)s in between (but they’re not important for the question). The server is running Ubuntu 11.10 (Oneiric Ocelot) ‘Server Edition’, the system from which I do my setup and testing runs the 11.10 ‘Desktop Edition’. We where running our shares with Samba (which we are more familiar with) for quite some time but then migrate to NFS (because we don’t have any Windows users in the LAN and want to try it out) and so far everything works fine.

How to auto mount an ssh file system on demand with an RSA key

I am trying to auto mount a folder from my raspberry pi (/home/pi/server_folder), to a local folder (/home/my_name/raspberrypi). I can do this with sshfs (auto mount in fstab) when I set up a blank rsa key, but when I try to use an actual key, like 123, the raspberry pi filesystem wont mount. This is pretty obvious, since I have to supply the passphrase, but is there a way to have it ask for the passphrase when I first try to access /home/my_name/raspberrypi, or do something similar to that? Because if someone gets my laptop, they dont need to put a password or anything in to get access to my raspberry pi, if I leave the rsa key blank. I have looked into autofs, and autosshfs, but autosshfs won’t download, and autofs doesn’t explain how to mount with an actual rsa key (well, I haven’t found a guide on how to). I’m using arch Linux, latest version. Here is the fstab entry: