I'm thinking of a much smaller container. More like a tub than a pond. But I had also assumed that a coon would just dive in and go after what he wanted? My chain of thought was that keeping fish would cut the mosquito problem but maybe make an even bigger mess when the coons were catching fish. I can just see one going after fish but doing in all the plants in the process. I have not really been up close to any in the last 50 years or so. Maybe they were just more impressive when I was smaller! One certainly did a job on my sister's house when they had a young one.
Well I thats why I was thinking maybe having the water level lower could help, and anything that can use around the edge of the tub to make it harder to climb on could help too.
I do know another option you could use is a motion activated alarm/light thingy. I saw it in Fosters and Smith where they have devices that are motion detectors and when something passes by, an alarm and a light goes on. I don't know how many neighbors you got though so I don't know if the alarm would be the greatest idea, but most of the time at night, if you shine a light at a coon, it's normally enough to startle them... Well for most "normal" raccoons..
Only other thing I can think of would be to use netting over top of it..... I use the green fencing stuff from Home Depot on my 300 gal tubs when I have to leave the fish in their over night if the pond hasn't filled, and it's kept them fairly safe, and it's strong too.
Oh and that would be one of the other reasons I recommend mosquito fish. They blend into most pond surroundings. They aren't going to be all that noticeable to a racoon at night, especially since the love to hide underneath plants. Look into fish that are natural colored... they blend in better especially at night.