It sounds to me that you would make a very strong media strategist for the Labour Party as it stands, but I assume you wouldn’t want the job. If I think back to Obama winning his election he has a very nimble and bright team of helpers around him. As Corbyn cannot rely on his own parties support he should build his own team, 20 or so people whose focus is on the media and messaging. He can use the increased fund from the 200,000 new members to put it to use at organising the messaging, purchasing materials, running measuring and testing ads on social media to create a strategy that works.
Trump also has an amazing knack of branding individuals he wants to attack. At rallies he adapts his slander to see what lands best “Crooked Hilary” “Lying Ted” etc. He’s a great tester of his own messaging and he does it well.
Having a media strategy that evolves may be enough, but if you don’t start now, the left will not be prepared for a general election and will loose horribly. The only options are to fight strongly via traditional media or prepare to be gutted by the first past the post system.