But that doesn't solve the problem. If the problem is, "East Oregonians feel disconnected from West Oregonians", I don't think there's a way to split Oregon that results in a net equal number of new representatives and simultaneously addresses the "we're too politically divided" concern.

Yes, you could slice Oregon in half horizontally and maintain the same number of reps, but then you'd have two new states with the East feeling divided. If you split it vertically, then you have the problem of uneven representation.