Networking :: Automatically Pass A Password To Rsync For Remote Host?

I need to be able to use an rsync command in script that will be run by cron. And it needs to be able to pass a password to rsync so that the remote server it's connecting to will authenticate.

I cannot set up ssh keys between the two servers, it's not an option. I cannot use any other language other than bash, it's my only option. I know this is highly insecure, I have no other option.

So far I have this:
rsync --rsh="/usr/bin/ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o PreferredAuthentications=password" -raxv /source/dir/* user@remotehost:/target/directory/.

This allows the script to ignore host verification and goes directly to the password prompt. I need the script to fill in this password prompt with the password that is stored in a variable.

I tried using expect, but I honestly don't know the syntax, it just keeps failing. A lot of the examples I'm finding online for expect starts off with a "spawn", which i don't have installed, and not sure if I have the ability to install it yet.