The best solution I have found for cars with blind spots is a set of these:
Can get them for cheap at any store with an automotive section and while they won't give a sense of exact distance, once you get used to them you don't have blind spots anymore, and you don't need to crane your neck either.
I will probably jump on one of the aftermarket back-up camera systems though. Never been excellent at backing into spots, and they are just too darned cool.
