You can also use moped or motorcycle mirrors on most bicycle handlebars, by using an old seatpost clamp. I have pics and some details about that in my Dayglo Avenger and CrazyBike2 threads (the DGA thread is shorter and should be easier to find it in).
FWIW, I considered an electronic setup (before I got into ebikes, and pondered it afterward a few times), partly so I could record it, but several things made it impractical:
--no screen I could find (locally, used, mind you) was bright enough to be seen in direct sunlight *and* in total darkness.
--The closest I could find would require futzing around in menus to adjust screen brightness between day and night riding, or else be blinded by the screen and unable to see the road. (actually only one even had a knob for brightness, and it *might* have had 2:1 ratio at best).
--The cameras also tended to have problems working well in both situaitons, especially wiht contrast--when any really bright light source like a headlight would hit it in less than full sunlight, it would dim the whole output so much that you could ONLY see the headlight, making it useless to see all the other things in it's view. Some of them were so bad that only the brightest headlight would show up, and all the ohters would be dimmed out to nothingness, so if there were really bright lights *behind* some other, closer, vehicle, you coulnd't even see the closer one!
--power consumption of both cameras and screens was very high, and would have required as much or more power than all my automotive/motorcycle lighting, so would need it's own large battery for any decent length ride.
--if power failed for any reason, I owuldn't have a rearview mirror....and if i had a "manual backup" already installed, I woul dhave no need for the electronic one anyway.
--Phoenix sun is very very intense in teh summer, and I have had numerous LCD devices permanently damaged by even a minute's exposure to direct sunlight in the middle of the day in summer, form the heat generated inside them by it I think--they sometimes recover partially, but are often much darker than they were before--permanent twisting of the crystals or something maybe. Either way, stuff gets reallly hot really fast and breaks.
So far the Cycle Analyst has survived, but even one of those has a little darkening from repeated such exposures (unavoidable while riding, depending on time and angle of sun and direciton of ride, etc. ). Completely destroyed a PDA (used for Veloace) like that, once.
--Theft is a big problem...somtiems I'm surprised my bikes don't lose stuff off them when I hav eto leave them, but It hink people are probably afraid to touch CrazyBike2 half the time. :lol: But stuff has been stolen off my nicer looking bikes I used to keep (so now they're all fugly as it seems to help).
Nowadays I would bet that everything but the screen brightness in direct sunlight problem could be dealt with for a reasonable price...but the screen is still a problem, either in cost or in brightness (or in complexity of *changing* the brightness for day vs night).
But it does stll leave the sunlight-damage and theft and power problems
