Stephen
Forum Vendor
A reversing camera above the numberplate can never replace mirrors. How on earth would it show if my elbows were still attached?
But seriously, other than issues of where to fit the screen, being waterproof, being easily viewable in bright sunlight, etc., my biggest concern would be the blind spots from a camera which is effectively behind the bike.
Going a bit more lo-tech, I bike I saw some time ago had a convex mirror strip in the dash. If positioned correctly, that could be brilliant for conventional blind spots, although as a replacement for conventional mirrors there would be far wider area behind that was obscured.
I once rode a customers bike with a convex mirror, although I first thought it looked ridiculous it did eliminate a large portion of your blind spots