Where do you get those great diagrams? They are much better than the manual I have.
I did figure out after the fact that I could have just removed the filter without draining. However, I tried to "follow the book" and ended up making a mess. I opened the drain plug up under the cowling with my funnel in place. However, since I needed a long funnel neck to get the drainage out to a bucket, the oil overflowed the funnel because it didn't drain fast enough. So..., in my effort to avoid making a mess, I made a bigger mess.
You're also certainly right that the 4500s have a variety of hydraulic setups. The manual I bought doesn't show the setup that I have. I missed that extra screen filter. Also, the section in my manual that says "Power Steering Reservoir (Except Ford 4500)" also doesn't match, since it is what I have. It looks like there are at least two types of PS setups.