an update: After much searching, I found that other people have found a solution to this and that solution is the particleSamplerInfo node.

after all my reading, it seems all I need to do is input the opacityPP into the particleSamplerInfo node, possibly add a reverse node, then output the p.s.i. node to the transparency of the fluid texture.

For all my efforts, I can attach the p.s.i. node to the transparency, but I can't hook up the opacityPP to it for some reason. Can anyone help?