Dually Lowering and Frame questions

Got a few questions about frames and lowering. Bought my 86CC Chevy dually a few weeks ago and the front was already lowered but the rear just had the overload leaves removed and a few of the regular leaves removed. I lowered it with a schackle kit just using the front schackles so far but what im curious about is what is everyone doing for frame strength when putting in C notches or is anyone towing anything like a 5th wheel with one the frames been modified on. After I put some taller tires on since I only have 27" on there now Im waiting to add the rear schackle to see what height is going to be. That and i really dont want to cut the bed supports. anyway here are some pics. Im also thinking before i do any serious towing ill change the bags over to a real setup instead of the home made setup I have now. People do interesting things is all i can say. LOL

some good reading here...