How to partial trace over an odd number of Majoranas?

Say we have a Hilbert space of $2N$ Majoranas. Typically we pair the Majoranas $a_{2j},a_{2j+1}$ into complex fermion creation /annihilation operators
$$c_j = (a_{2j}+ i a_{2j+1})/sqrt{2},quad c_j^dagger = (a_{2j}-ia_{2j+1})/sqrt{2},$$

and define a Hilbert space of dimension $2^{N/2}$, or one qubit per fermion, using the Jordan-Wigner transformation.

Say we have a state $rho$ in this Hilbert space and we would like to partial trace over $m$ Majoranas. If $m$ is even, we can do this in the basis defined above, since we are just partial tracing $m/2$ out of $N/2$ qubits. How can we do this if $m$ is odd? (as is done, for example, to compute SYK entanglement entropy in Figure 7 of this paper)?