  As liquid xenon TPCs increase in target mass while pursuing the direct
detection of WIMP dark matter, the technical challenges arising due to their
size call for new solutions and open the discussion on alternative detector
concepts. Proportional scintillation in liquid xenon allows for a single-phase
design evading all problems related to the liquid-gas interface and the precise
gas gap required in a dual-phase TPC. Aside from a different scintillation
mechanism, the successful detection- and analysis scheme of state-of-the-art
experiments is maintained in this approach. We study the impact on charge
signal analysis in a single-phase detector of DARWIN dimensions, where the fast
timing of the proportional scintillation signal allows for the precise
identification of the single electrons in the ionisation signal. Such a
discrete electron-counting approach leads to a better signal resolution for low
energies when compared to the classical dual-phase continuous method. The
absence of the liquid-gas interface further benefits the S2-only energy
resolution significantly. This reduces the uncertainties from the scintillation
and signal-detection process to a level significantly below the irreducible
fluctuation in the primary ionisation. Exploiting the precise electron time
information further allows for a powerful single vs.~multiple site interaction
discrimination with 93% rejection efficiency and 98% signal acceptance. This
outperforms the design goal of the DARWIN observatory by a reduction factor of
4.2 in non-rejected multiple site neutron events.
