I'm not at all familiar with the Bernina you have, but I would think that if it is on a carriage system so that the sewing machine is moving over the fabric, rather than the fabric moving under the machine, then you would be able to do ruler work.
Rulers and templates for most longarms are 1/4" thick so that they don't go under the hopping foot, which is also about 1/4" thick. When using the ruler you also place an extension plate on the sewing machine so that there is more flat space to keep the ruler positioned. Without that, the ruler tends to tip and then the needle is likely to hit it. I'm sorry, I don't know if any of that applies to your machine.