For a little deeper fishing, we did a show on Lake Of the Woods in 2007 (available on DVD – has some excellent animations) with the identical situation you are talking about. Humps with lots of rocks. Our best technique was Bottom bouncer fishing with spinners (or Slow Death).
Couple of refinements for this type of fishing. First you need to keep a steady pull on the bottom bouncer. Do this in calmer weather with your trolling motor – in rougher weather you can drift but be sure to use a drift bag to give you a more consistent pull.
Next, use a heavier bottom bouncer. 2 or even 3 ounces depending on depth. The heavier bouncer will keep your line straighter up and down (instead of dragging way behind the boat). This allows you to adjust quickly to just tick the bottom instead of doing a hard drag. You might even hold the bouncer just above the bottom and just touch it down every once in a while to stay close.
Use a fairly short snell (3 foot) and a small spinner blade (#1) to keep the spinner from dragging too much. As mentioned, Slow Death is also very good for this as it has very little weight.