I'm just a weenie, but I thought I'd post anyway. Backpacking, I do fly fishing for trout. My bass fishing is day-trip floating and "normal" fishing. I use a 4 wt, 8'9" rod for backpacking. It breaks down into only 2 sections, and I just strap it to the side of my backpack, and I'm OK with it. It could be seen as overkill - the lightweight advocates in fly fishing would chide me for using this for brook trout...I do think I will eventually get a 2 wt rod just for brookies. I am also catch-and-release unless I fish stocked waters, but I am pretty much a wild-trout man.
On line weights for bass, crappie, etc., I would offer that 2 lb line does break easily around tree stumps, snags, etc., and I like to keep stray pieces of mono out of the water as much as possible, they can be hazardous to fish. I would recommend going with at least 4 lb even for the small guys just to be a little on the "green" side of things.
Blue gills and crappie, by the way, are seriously yummy eating fish.

"weenie" meaning I do heavyweight stuff because everything I have does everything......it's not just a budget issue, I get attached to my favorite gear and will go to any lengths to pack it along on a backpack........:-)