Abstract: In Si/SiGe spin qubits, much attention has focused on high-fidelity and tunable gate operations, yet achieving the same goals for readout, which is a core requirement for quantum error correction, has received less attention. Traditionally, single-electron spin qubits are read out using either of two methods. Elzerman readout relies on proximity to a reservoir. Parity readout requires an additional electron in the double dot system used for readout and a large valley splitting to achieve a large singlet-triplet splitting. Here, we present a reservoir-free readout scheme for single-electron qubits in a double dot that does not rely on additional electrons or the need for a large valley splitting. This readout scheme uses photon-assisted tunneling (PAT), enabling spin-to-charge conversion and readout via a nearby charge sensor. We show that features in the energy dispersion arising from random alloy disorder may be used to optimize the PAT drive parameters and achieve high-fidelity and tunable readout. To provide physically realistic and accurate estimates, we develop a new scheme for computing localized electron states in a double dot, which allows us to make use of the MaSQE simulation tool. These results pave the way for implementing a new high-fidelity readout scheme in single-electron qubits.