Just a thought, if one buys a wheel other than the proper Honda, do you have to tell the insurance Company as perhaps one would not be insured as it would be a 3rd party item if it was put on the road ??
It's a good point, certain insurers will look for any way they can of paying out in the case of a claim.
If I was an insurer, I think I would be a lot happier if you fitter a steel wheel with the correct size matching tyre fitted, rather than one of the spacesaver spares. When I first used one I was shocked how much different the diameter is from the standard tyre - handling is severely compromised, even below 50mph, and it can't do your differential any good at all!
I would think an insurer would have a hard time arguing that a non standard but identical sized steel spare would be detrimental to the cars safety, especially when they are happy for you to put a wheelbarrow wheel on. A car would pass an MOT with such a wheel on, without any comment, so I think they would never be able to prove that it would be a contributing factor to any accident.
You could always tell the insurer beforehand that you carry a full sized spare, and leave it at that. I can't see why it would be a problem - I'm not even sure the steel spares have a maker stamped on them anyway. Spacesavers are only meant to be used as a temporary fix, to get you home or a garage, I think if you treat the full sized steel spare similarly, you won't go far wrong.