I live not far from Horseshoe lake and fish this area quite a bit: great multispecies lake! For LM, check out the large, shallow bay on the SE side of the lake. It is directly south of the big island.
IMHO, topwater is a low-percentage presentation on shield lakes in this area. I have good luck with spinnerbaits, chatterbaits, jigs and plastic stick baits. In that bay, you will need fairly weedless presentations.
Good luck! Drop me a line if you come up this way.