What ship combinations (besides two Cutlasses) can fit in the Landing Bay and successfully be launched and maintained?

Like the Javelin's hangar, the number of ships allowed depends on the size of those ships, specifically. The Landing Bay is currently spec'd to be 30m wide, 65m deep running underneath the main spine of the Endeavor, and 10m tall. The included facilities and systems can accommodate possibly to 4 craft as space allows. Remember, that the general rule in Star Citizen is that 'if it fits, it sits' (with a max limit of four with regards to munitions/stores/etc.); so you can calculate the space any individual ship using those measurements.