You can purchase any size you want. There are plenty of resources online to find the one you want..... buy one and see how you like it. Or..... you could mock one up with cardboard or plywood and try it. (not under way, of course) In the end, it is you that will make the decision.... so don't be afraid to experiment and evaluate the changes objectively.... so you can go back to the original set up. Don't throw the old wheel away, btw.
When you say "easier to get around the wheel".... in what circumstance is the hindrance most annoying? Is it for crew movement, for the driver going over to adjust something, etc.? There may be other ergonomic or procedural changes that might make your cockpit mobility less critical to happy sailing.... moving the winches, for example, or your steering position (move to the side or sit in front, perhaps)