Hi Gavin,
Ya, this is sort of a bind. Your SaaS controller is incompatible with the 4.2 agent you're trying to connect with, yet you need the 4.2 agent to support the nodejs version you're using. The good news is that the 4.1.10 version of the agent should support the nodejs version you're using with your app. Could you give this a try?
Best,
Rachel