Those rear springs are not under nearly the same tension as the front, so removal/replacement is not as dangerous using the right compressor. That said, I've used aftermarket rubber spacers on the tops of my rear springs in my streetrod, and those springs are out of the front end of a 77 450SEL. The coil diameter is almost the same as a late 70's Chev Nova.
I wouldn't consider those 'redneck' inserts that can be used to extend the spring because they make the spring act like it has 2 coils cut out (because the device locks the 2 together) and drastically affect ride quality as a result.
The rubber spacers are dirt cheap, fit great, easy to put in, and you can get away with leaving the stock rubber rings in there too if its necessary.

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1986 560SL
2002 Toyota Camry
1993 Lexus