Recommendations for analog tri-state buffer?
Different `4066 devices have very different on-state resistances under various conditions.  For example:

TI CD4066B is around 400 ohms at 0v input with 5v supply, but 100 ohms for the same input voltage if you increase the power supply to 15v.  Cool it from room temperature to -55C and it's down to 70 ohms.

TI CD74HCT4066 is only 25 ohms for 0v input with 4.5v supply, at room temperature.

There are of course other manufacturers and other switch chips.

If you had a slightly negative power supply (-1V or so), you could use the FET switch with an op-amp follower circuit driving it and taking feedback from it's output, both powered from that negative rail and thus attempt to achieve unity gain from input to output of the assembly.