Multiple Ground Referenced Sensors on Single Floating Supply
I've had the same constraints and had to find the solution that others are talking about. I don't know what capture speed you want or what sensors you have but there is almost an integrated solution using TI's chipsets like this: -

This is a generalistic circuit suitable for multiple options but you can get more bespoke variants of the same theme suitable for the individual sensor types. The solution that I ended up using was with ADI because it was self-powered thru the isolation device: -

(source: analog.com)
The ADuM5401 has a small DC-DC converter internal to the device that can provide enough power for the front end AD7793 chip. You might also consider the good-old isolating amplifier: -

For less problematic ground potentials you can even use the LTC1043 isolating capacitor thus: -