I know they have to feed.  Any tips on catching them late summer?

for the most part, fish deep

stay deep and look for standing timber

A buddy of mine has been catching them early and deep on hal flys and small jigs.

I catch them all year around here, right now I am catching most of them 6-10 feet down on a minnow tipped popeye jig (chart. and black or pink and black). Find deep cover and let the jig slowly fall (no additional weight between the jig and bobber), if they are there they will almost always fall for this!

Been catching them on Beetle spins and small spinner baits while fishing for other Sunfish this summer. I've also been using live worms but expect to catch every thing in between with worms. Maybe try small tubes haven't tried them in a crappie pond but I think they would work as well.