Floating voltage measurements
An answer in another question sparked an idea for this.

You maybe could use a high-side current monitor circuit like INA168:



This allows the input voltage to have a common-mode offset of up to 60 V and will output a ground-referenced 1-10 V signal for your inputs, with an appropriately chosen RL. You may even be able to get a gain of less than one, though I haven't read the datasheet closely enough to know if this is guaranteed to work.

If you can reduce the voltage range to be measured to something like 0 - 1 V instead of 0 - 10 V (say with a simple resistor divider), you can use the somewhat similar INA193, which allows up to 80 V offset, but has a fixed gain of 20 V/V.

If you can't reduce your input voltage range, you could try building your own circuit with a similar topology but lower gain. Your accuracy would probably be reduced due to inability to match components as well as TI can do in a single chip.