Flatlander,
Your friend Bill needs more data. A slot limit is an excellent idea, but is only one tool available. Identify the sunfish. Make sure they are bluegill. If not, let's talk.
Florida bass won't survive ice covered ponds.
Dynamics of a fish population dictate the course of action to take. Too many bass in a system? Lengths compared to weight prove it. If 30-40% of size class of bass are at least 20% underweight most of the year, that size class needs to be thinned. Slot limit.
If sunfish are stunted, it may be overcrowded bass, it may be a sunfish problem. Identifying sunfish will help make a decision.
Always remember these principles...a balanced bass/bluegill fishery has different size ranges of both species of fish. In other words, balance means bass 4 inches, 8, 10, 12, 14, 16,...etc. Same with bluegill. If you have bluegill from 2 to 10 inches, with varying sizes of bass, things are clicking.
The next principle...you are trying to manage a predator/prey relationship. Fish eating fish. Bluegill are the backbone of the foodchain for bass.
Third, harvest is a huge tool, especially in older or larger lakes. Cull bass, slot limit. Cull smaller fish. Remember this...a 20 inch bass can eat a bass nearly 12 inches long. Big bass have big eating habits. And, to that end, remember this. This next nugget is big. And, I didn't learn it from Fisheries management 101. From experience, I learned...a four pound bass won't grow in a skillet. With that in mind, every eight pound bass on the earth weighed four. My point? Preserve the largest fish, catch and release all large bass. They are crucial to the success of a bass/bluegill fishery.

Teach a man to grow fish...
He can teach to catch fish...