You don't say where you live, but here in Southern California, Ballerina is a large climber. I've seen it go 25' into a pine tree! In one season, it went to the roof of a single story house. Most of the Hybrid Musk roses you'll find on Help Me Find could do well for your use. Just check the heights to see what will fit your need.
You may want to rethink the idea of Mermaid for you Zone 7b garden. Help Me Find reports it's hardy in Zones 8 and 9. From experience, Mermaid doesn't tolerate hard freezes, so if you select it and have them with any frequency, try protecting it by growing it on a wall. If flexibility is important for this planting, forget Mermaid all together. The wood can be used to create tough, hard wood flooring! It's brittle and resists bending, unless the rose has the idea first. It's a great climber, one I wouldn't choose to be without, BUT, I live in Zone 10 with undertones of 9, where it gets 40' to 50' in just a few years. And, those thorns ARE wicked! Huge, curved and very sharp!
William, I don't know if you're aware, but Help Me Find is actively soliciting commercial nurseries to become paying sponsors to advertise here on this site. I notice your employer, Jackson and Perkins, isn't a paying sponsor. Perhaps, you being a J&P employee, could assist them in getting the powers that be at your office to become a paying sponsor to help support this wonderful resource? I know everyone appreciates any and all assistance in answering the questions posted here, but I do find it unfair for you to advertise your employer's products here, free, without them paying for the privilege. If you can, please, contact the appropriate people in your organization and promote Help Me Find to them so they can assist in keeping this site the premier rose resource it has become. Thank you! Kim Rupert