The structures would be a good idea. Try to cover the range from bottom to 6 ft (or below max ice depth). If the SMB and LMB are fat and you are catching a few less then they are probably moving toward a balanced status across all size ranges. This would be further confirmed if the forage in the smaller sizes (1/4 to 1/3 the length of the most numerous sized bass)are less than they were (small RB #s).
See this thread for great structure ideas with pics.
http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=92463#Post92463