You could use SSH with host-based authentication. Then you would not need those script and simply use SSH and SCP normally, without the need for passwords nor user keys.
With host-based authentication, any user connecting from a predefined set of machines (here it would be the host) is automatically authenticated on the target machine (here the board).
You need to modify the SSH
server configuration on the board, and the SSH
client configuration on the host (which you can do without the need for a root access).
Here is a tutorial that should get you started.
Note that if encryption is not mandatory and performance is of issue, you can use the same host-based authentication scheme for RSH
access.