Hello all you awesome LDS users (and lusters like me

). I'd like some of your opinions on my current predicament / quandry.
Part One: I currently play through an Ampeg 8x10e in a loud indie rock band. I can't say that I'm "dissatisfied" with the way that the cabinet is performing, but it is big and heavy. I'm really going for a super clear, low-end-of-a-piano type sound. I need to be able to hear the notes articulately all the way down. I do a lot of tapping, and I play on a six string, and I have a relatively high gain sound. I've found that the low B on my six string isn't quite as full as it should be and there is a slight volume drop when the full band is going (two volume -war driven guitarists, and a drummer who likes to beat his drums severely). I still can't believe it. Basically I need a cabinet that will allow me to fulfill my duties as a bass player (hold a solid low-end and fill in the sound) while also allowing my more melodic parts to be present in the mix.
Part Two: In recent weeks, I have made the decision to try and supplement my income with more and more bass playing (being in a stary-eyed rock band doesn't quite pay the bills). With that in mind I have taken to the old bass player stand by of joining a wedding/bar/cover/party band to take in some extra cash, along with teaching. Obviously I can't take my mammoth 8x10 rig into a small band setting like that, so I have been thinking more and more about getting a medium sized rig (around 500w) that would be easy to transport to a wedding or bar without much hassle.
Part Three: Throughout these meandering explorations of cabinet/amp possibilities that I think most bassists have gone through at one point or another I have stumbled upon the idea of getting a "smaller" cabinet that I could bring for smaller gigs with the possibility of adding another cabinet on to the rig for larger gigs.
So, the conclusion/idea that I came up with would be to have a smaller cab (like a fEarful 12/6 or 15/6) and be able to add it to another, larger (or similarly sized) cabinet for my gigs with my full band. Would I be able to add one of the cabinets mentioned above to another LDS cabinet and get the kind of sound that I am looking for? I was also looking into getting two fEarful 15/6s and using them with my QSC PLX 1602, but that would be runnign them in stereo at 8 ohms each, and I'd like to run my amp at 4 ohms to get more power (refer to "volume driven guitards" as mentioned above

). The main stumbling block is that I am not sure if they would be able to have the same presence and authority in the full band setting if they were not being given their due power.
The other option is to get another power amp (definitely a QSC), but I think that might be more trouble than its worth. Please let me know what you guys think.