there are 360 cams on the market now that can be added to pretty much any machine if one wants to add them
and no shortage of other cams you can add about any where you feel the desire to mount and wire them in!
as for where is the BEST place, that is an impossible question to answer, as everyone has there own opinion on anything and everything!
Lastly, there are many issues with cameras, and why many don't use or really want them
when working in dusty places lens get covered/dirty and sensors become useless and its time consuming to keep getting out of a machine to clean
next is most screens are honestly TOO small to be of use(all the more so to older operators who's eyesight has faded over the yrs!
and lastly, many screens are placed in places there not really user friendly , causing operators to take there eyes off what there doing too see!
YES camera's can be nice and helpful, but honestly, a GOOD SKILLED operator is able to do it all without them just fine and be safe!
ain't no shortcut to skills and experience! IMO