The OP specifically asked about "side cameras", not interior cameras that happen to be able to see "some" of what is happening outside you car.
I have nothing against interior cameras as they have their value but they are a completely different animal than true lateral facing side cameras that can actually accomplish what the OP is asking for. For this you want cameras on either side of your vehicle that can capture a wide clear image of everything to the left or right hand side and as close to the pavement as possible as near to your vehicle as possible.
I have used a variety of side cameras over the years but especially like the Mobius cams with the "C2" lens option as side mounted cameras for their excellent coverage and acuity. I mount them over the fixed glass rear panes of glass in my pick-up truck.
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The is an older example I had handy. Recent set-up produces better image quality.
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