High sun, between the hours of 11am-2pm is a challenging time for me also and I am by no means a charter captain or winner of any notable tournament series on Lake O but with that being said; I have had more success recently in those conditions limiting my spread and pulling rods to (5 rods only), lengthening my leaders on my thumpers and dipsys (9-16ft) and using only natural colors (black, silver, green) often with little to no additional "jazz" (UV tape, glow etc). I have not altered speed too much at these times but I am sure that someone on here can provide some feedback.
Hope that helps!