I lived there for six years and always did pretty well with the largemouth.I never could figure out those smallmouth but I have seen some really good ones pulled out of there. Lake Whitney is a very clear, deep Rocky lake that is full of shad and known for its really large stripers but its a little too early for them or the whites (or sand bass that they call them). Towash Creek on the north and east bank was the best that I have found for largemouth. Shallow diving crankbaits on the rocks and black and gold spinnerbaits in the brush. Soft plastic colors for regular worms and lizards Pumpkinseed. Glimmer blue zoom flukes.
It would be a good idea to call the state park and ask if there is a Golden Algae Bloom fish kill right now. Whitney and Grandbury have been hit hard over the past ten years. Towash Creek has a fresh water creek in the back of it that always draws the big bass there during the kill so don't panic if the fish are floating! Lol!
In front of the State Park boat ramp there is a long wide creek with lots of shallow brush that has always been my second place to hit.
Hope this helps! Good luck!
P.S. when entering into a rock cove, always stay in the center! This lake has eaten many lower units over the years!