With you all the way on this one MikeN.
Being sick of the 'stout copper wire in the track' trick, I made a double ended split-shell clamp type thingy with a full-circle ridge to engage the groove on the two basic sizes (15 and 18mm id), plus a tapered bung to protect the cb end female taper as you rightly emphasise. Works a treat and is usually not here, as someone's borrowing it. My pic won't attach as the res is too high and I'm a moron when it comes to digi-tech, but you'll know what I mean. The beauty of the full-circle ridge is it is gentler on the inner race then the grub screw method - but the downside is it obviously has to be turned up, and in my case also needs a simple 2 legged puller to operate it.
I don't know why there isn't a commercially available equivalent out there - or maybe there is and I just haven't spotted it? Or maybe there's a limited-production opportunity out there (for anyone who wants a sure-fire way to lose money!).
The same principles apply to any bearing with no usable space behind the inner race, and my box is also rather full of such contraptions that did something useful, usually only once.
I think the up-to-60mm AF infinitely-adjustable socket spanner created for getting the crankshaft sprocket nut off my RE takes the biscuit in terms of time spent for a limited return! But where the hell do you buy a socket that size on a Sunday? And if you could, how much would it cost!? (Even if it was the very end of Sunday before the thing could be brought to bear owing to the time spent milling and turning it out of a chunk of 3 inch hex bar in a small workshop . . .)
