What type speaker component to fill in low range of trailer 5.1 system ?

[kbarbr]

I have a large Jayco travel trailer that came with five small 3" inexpensive ceiling mounted speakers - Magnadyne LS3CMW - which are available on Amazon for a whopping $22/pair (high end ! ! ).
See the photo below.
But with speakers that small there's hardly any low midrange, and definitely no bass.
The specs say 160-20kHz, but who knows. Prob not below 400Hz, definitely not below 160Hz, and that's the problem. They sound ok otherwise.

So how could I fill in that gap ?
I just need a little filler on the low end, not subwoofer range.
And something inexpensive - it's never going to be a high end system and I don't really need one, so no replacing the whole system, etc - just something that more or less works.

I don't even need two speakers as it's going to be getting down to the non directional end of the range. If I could get away with one that'd be great.

An idea - there is a space in a lower cabinet where I could build an interior enclosed box, and put in a 6" to 8" speaker, with x-over.
(The Sony receiver I have does have a subwoofer out, for which you can set the cut-off frequency at various points up to 200Hz, if it's a good way to go.)

What would you do ?

• A 6" woofer ? an 8" ?
• An 8" dual cone speaker ?
• something else ?

Remember, it's a low-fi system, not really worth throwing a lot of money at.

Thanks !

Kent

What's here now : 5x Magnadyne LS3CMW