Just in case you're wondering, that drain pipe is for future access to an outdoor A/C unit (wires, tubing, etc.) that runs under my patio and to yet another flower bed by the fence. It'll be it's new home when it needs replacing, just too noisy next to the back patio as it is now.

You don't train Lady Banks, you simply control her as best you can.

I speak from experience.

Oh, my main concern is the positioning of their beds, the closer one is 11' from the North end of the wall, whereas the other is just a foot away.

Should I trim the ends when closer one reaches the North end of the wall or wrap them back toward the center via the top bar?

'Trim' is not a verb that springs to mind when considering a Rosa banksia! You will see what she does...she has a mind of her own and you will be trying to beat her into submission on a regular basis. They call her a 'house eater' around here. I have several and use them to cover ugly chain link fencing, or a large arbor over a swing. Don't worry about cutting too much - you cannot hurt it. The only question is whether you can tolerate the maintenance required. You're going to have a hard time keeping those windows from getting gobbled up. Your desire to cover the blank wall with some greenery is understandable but you may end up opting for something a bit better-behaved. See link for a photo of ONE of mine, taken when the plant had been in the ground about five years.
Good luck!{{gwi:563755}}

You can train it along your trellis, but may begin to grow faster than you can trim it. It will try to go over the roof.

I had a white one that ate my house. I cut it back to nothing every year, but it grew so fast I could not keep up with it. I finally gave up and removed it because it was prying up the shingles.

But I know why they are so beloved- look at formandfoliage's picture! Wow.