Small Monsoon-planar speakers - any help!

[Spasticteapot]

I have a pair of Monsoon planars. With a siutably large baffle, they're supposed to be good down to around 300hz. They're not super-powerful, but I don't need much oomph- just decent quality.

Of course, these need a woofer, so I'm hoping to use some Silver Flute W14RC25-08 5.25" drivers in ported boxes. They're cheap ($17.50 locally) and work well down to about 55hz.

Here's my box in WinISD. I'm not very good at using it, but I think I managed to get a reasonable design. I'm hoping to turn it on its side to make it wider than it is tall; on top of it will be mounted the Monsoon panel with an extended baffle.