Ahh. Thanks for that.

I'm taking option one, but limiting it to one loop and a little recursion to make it all a little more aesthetically pleasing.

5 minutes for disks 1-8, but disk 9 is really pushing the envelope, it's taken 15 minutes to get the gap down to 0.000299999999987977.

Maybe I should set a higher limit for the gap - it might catch all the "perfect" solutions.