I have been using a sparging setup for my last several BIAB brews. When I brew 10 gallon batches, I can't fit all the grain and water so I do a sparge with the extra water at the end of the mash. I came across a bunch of 3-5 gallon food grade buckets from laboratory supplies (microbiological media supplies). Conveniently two of them nest inside each other rather loosely so they don't get stuck together. I drilled the bottom of the shorter one with a bunch of 3/8" holes. I insert it in the other which leaves about a 1.5 gallon space in the bottom bucket. I pull the bag from the mash, drain just enough so it isn't pour all over and then quickly lift from the mash to the drilled bucket. I use a pot lid to push down on the bag to squeeze, dump that wort from the bottom bucket into the keggle, pour on my sparge water, let it drain and then squeeze again and dump. Very straightforward, not too messy. Here's a few pics of the setup. I realize it might be hard to get these buckets but perhaps it gives you some ideas.
