Well, speaker design is about trading efficiency for BW, so based on published specs, then a max flat cab is 2.5 ft^3 net tuned to Fs and you'll need to either add enough series resistance to flatten it or digital EQ or design a suitably large BLH to tune it to as low as Fs*Qts/2 = 5.5 Hz, though once below Fs, power handling will quickly become limited to 'flea' power, so realistically only design for ~32 Hz, preferably corner loaded.

A stereo pair of MTM or even just duals where it rolls off the upper woofer (2.5 way) tuned to ~32 Hz are good options if super loud isn't a goal; or if needing a relatively narrow horizontal directivity, then a 9844 baffle layout.

XO point would be based on layout/desired directivity and/or HF horn choice.