When the water gets hot, Crappie will utilize shade ... be it from an obstacle above/below the water's surface or from depth if obstacles are not present. The water may be 80-85deg on the surface, but 10-15ft down it could be 10deg cooler.
A 10lb weight on a rope should be enough to keep a yak anchored.
Fishing docks: find those that are in at least 15fow - have ropes or wires hanging down the sides (indicating brush/trees are on the ends) - and have lights, rod holders, or equipment visible that would indicate the owner fishes there. A fishing boat or pontoon moored there (rather than a ski boat, jet skis, etc.) is also an indication the owner fishes & may have brush under or near the dock. Pattern changes occur throughout the day, and may be no more than a change of location or depth. Shooting the dock would be the optimum method to be used.
Fishing Bridge Pillars: fish the shaded sides, and the down current ends. Vertical jigging, "Vertical Casting", or regular casting techniques should work. (Vertical Casting explained :
Crappie Pappy Article )
Vertical Casting works on docks (dock pillars) if they're stationary docks. FYI
The presence of Shad (or other species of baitfish) in the area is a good sign, but not a guarantee that fish are present. In those high water temps you may also find Crappie suspended out on an open flat, following or intercepting baitfish as they move across the flat. This is the general situation where most people Push jigs or cranks. Depending on your electronics, you may also be able to troll the area, or if there's some cover scattered on the flat you may be able to cast to those. The baitfish may be on or close to the surface, but the Crappie will likely be a foot or two below the bottom of the baitfish school regardless of their depth. You would want your baits to be no deeper than the bottom of the school's depth. (but always at least 1ft off the lake bottom).