I have fished Lake tomahawk on several occasions. good smallmouth lake, fairly clear and deep. There are some nice humps in the middle of the lake which show up on maps. As far as a map I believe there is one on the bassmaster site – one of those 3-D jobs like on the tv show. Anyway, the humps with deep divers or tubes are pretty good in the summer. Also, one idea would be to go up the canal to Mid Lake- very shallow and weedy, but a decent population of largemouth if it is not off limits. It seems to get very little pressure and is usually worth a spin- there are docks and weeds- both lillies/arrowheads and coontail/cabbage types under the surface. Shoot me an email or reply, Ill look around to see if I can find a map- I also have a good friend who grew up fishing the area and ill run it by him.
(I am assuming this is a bass tourney- by the way, when is it?)
Another good resource is on minocqua.org- they have guide reports that can lead you to the seasonal pattern, and if you email most of the guides seem happy to share info or book a trip.
Good luck. JJ