Tall Climber Spread On A Low Wall

I’d like to train a Golden Opportunity on a 4 foot wall so I can espalier the canes for a wide spread against the wall. This rose is described as having vigorous growth to 10 ft+ tall.
Question: If I let the canes grow to about 6 ft vertically and tie them horizontally, will the canes stop growing in length? Can I “fool” into more length?

If you can, shape the canes like a fan, you will get the most blooms from the laterals that will grow from the arched canes.

It’ll be couple seasons before there’s enough length to do that. My question now is how to determine which branches are canes that should be left to grow and which are laterals that can or should be trimmed.
Should I just deadhead the blooms and let the branches grow without trimming this first year in the ground?