I have some 12 lb high vis florescent green P-line, can the bass see this underwater? It seems it is made for slow plastic worm type use but I don't want to waste a lot of time before I find I'm not getting any bites because of it.

I use hi vis 10 lb Suffix on my spinning setup. I always use a leader with this line though, I just like how easy it is to for me to watch it sitting on top of the water for those weightless presentations. Those subtle bites are easily seen.

I don't think line color matters too much. If a fish will hit a giant Alabama Rig then I suspect they could care less about hi-vis line. That's just my opinion though.

An Alabama rig is a reaction bite. Dragging a plastic on bottom is not. My personal opinion, I would use a leader. I don't like braid or hi his line for slow moving baits unless it's just a must.