I'm somewhere between new and experienced, having played guitar and bass for years but only recently joined a band. My current rig is an Acoustic B200H head paired with a Carvin RL118 cabinet. It has enough volume to keep up with the other players, but the RL118 is so heavy. I considered an additional smaller cabinet to add midrange, thinking it could double as a practice amp. However, the Carvin is 4 ohms and that's the minimum for my head, so I can't connect a second cabinet with the 118.
I would like to build a modular rig that I could use for practice, and small to medium sized venues. I'm thinking about swapping the RL118 for a 1x15 and adding a 2x10 or maybe just a pair of 1x12's. I found a deal on a Rumble 500, which is lightweight and could be paired with an external speaker (but not my 4 ohm Carvin). Would I even need a cabinet with a 500? This is all used gear, too. I don't have mid-life crisis money.

Is this just another case of gear acquisition syndrome? Can I get some advice from the experienced folks?
~ Jay