Reinholt, I agree with you 100%.
There is nothing I can think of to counter Rhymer without completely altering what he does, and even then the only fair thing I can think of is having him operate kind of like Flight Controllers - only the squadrons activated at the same time get his ability. A large carrier could still activate him and all of the bombers around him same as now, but you wouldn't be able to park the 'Ball somewhere and just spam at Medium Range. The big issue there is, how do you explain that clearly?
I think the issue is that, if you take both Rhymer and Demo out of the equation, Imperials are in trouble. What do they have that can chase down Rebel ships? The Interdictor will help to that end, but it, too, has to be within a certain range to trigger.