I think in this case I`d be looking at a lightweight 2x10 or 1x12 - you already have a 150watt head so chuck that and leads/tuner into a backpack, bass in one hand, cab in other, pretty much sorted. My Ashdown RM210 cabs are pretty light, and the 1x12 is lighter still. Have to admit that Ashdown Studio 112 looks like it fits the bill though.