i'm not sure if it's still in production, but bag end used to make a monitor version of the S15X-D (S15XF-D???). i heard them a couple of times, and the bass player from darik and the funbags (darik) uses one. they sounded pretty darned good IIRC, and were nice and small.
I also heard a bag end TA-12F which was a floor monitor version of the TA-12 (since upgraded to the TA-2000 series) both that and the TA-12jr (since upgraded to the TA-1000) are great for bass as well.
all three are prety compact (more so than the cabs they are based upon) and do well as standard bass cabs by placing them upside down so they sit on a flat surface and project straight into the audience. If you can find any of them used i think you'd be pleased.
personally, if i was looking for a floor monitor far bass i would prefer the TA12jr/TA1000 floor monitor as those are probably the smallest cabs of the three and still do very well for bass reproduction (not the most low end, but you'll hear yourself clearly).