That is already an impressive "to do" list!

Here are some hare-brained ideas that you can easily improve upon based upon your actual eyeballs on the situation:

1.) I like your sediment pond for preserving the depth in the main portion of your pond. However, if you have tilled farm ground within the watershed of your pond, then you are always going to be filling your sediment pond.

Can you easily build a couple of "dry" peninsulas near the last water flow obstacle of your sediment pond. If you can drive your trackhoe to the end of the peninsula and extend almost to the dam/obstacle and then swing your load of silt back onto dry land, then that would be perfect spacing.

If you excavated an arc of silt around each peninsula every few years, that would keep an active sediment trap available for deposition, rather than having all of it run into your mail pond.

2.) Willows are one of nature's inventions for trapping sediment. Could you allow a narrow band of willows to exist on the dam/obstacle of your sediment pond? If water during the 5" rain was actually moving, then the willows would decrease the velocity and a little more sediment would drop out earlier from the flow of water.

3.) It sounds like you do suffer some bank erosion, probably due to wave action in your large pond. One of the easiest ways to prevent shoreline erosion is to keep your pond as much as possible at the exact same water elevation. When the water is lapping at a massive root system of terrestrial plants it is difficult to cause erosion. However, when your water level drops 18" during a dry spell, then the wave action is usually able to more easily erode the bare sediments of pond slopes. Then as the water elevation goes back up, "headwall erosion" can remove material up to your normal pool elevation and actually undermine your existing erosion barriers.

If you and your wife like the look, you could even rock your banks along some of the windiest areas. Just a 12" band of rock on fabric would greatly reduce wave erosion - if the water level always stays in the rock band.

I mention that option, only because you say you might be building a second large pond a bit further downslope. That second pond could be a supplemental water source for your main pond. Pumping water up only a few feet of elevation change is MUCH cheaper than pumping from a deep well. Further, the dock and any other shoreline amenities would always be at the optimal level to keep your wife happy.

4.) Yes, it would have been nice to put a guard on your drain pipe. However, being blocked by sticks is much more likely for water surface pipes. I believe your bottom siphon pipe is unlikely to be blocked. Yes, the local flow gradient would kill a diver if he stuck his arm in the pipe at full flow. But the rate of flow drops with the cube of the distance from the pipe, so it is unlikely to draw sunken wood into its mouth.

If you are truly worried, then you could add a second shallow automatic siphon system when you work on the dam. I don't recall anyone on Pond Boss ever complaining that they had too much emergency water flow capacity!

5.) On a 20-acre pond, you almost certainly do not have enough structure. Free pipe is a good starting place. There are a lot of creative structure ideas in the archive thread where members figured out the best way to utilize their available materials. I am sure you can do the same with your pipe.

Good luck on your pond improvements! Sounds like you will be creating heaven for both fish AND family members.