The Wallace experiment is certainly worth doing - especially if it's in a repeatable location.
It's only 4 miles, but the center point is nicely centered. That's a lot of hiking though, and looks like steep sides. The benefit of a canal is it's a straight line, and often you can drive alongside it. I don't really see this location being that practical. How do you get from one point to another?
I was planning on driving as much as possible. Location A is reached by Cherry Tree Spur Track but even if that's too overgrown, it looks like a 2km walk from Walhalla Rd. Location B by Pipeline Track or 1.5km walk. But Location C, I might need a canoe and then there's the issue of finding an accessible launch site. Maybe this location is not so great after all
I was attracted by the obvious centre point (which I think is really necessary to say something useful with this experiment) but I might keep looking, or maybe go up there and have a look around first.
As for the experiment generally, I guess my primary concern is controlling for refraction as much as possible. This site is full of such detailed information on refraction and, this might seem redundant, but I think it would be really helpful if it was collated into a sticky such as, "How to design a good curvature experiment" or "Controlling for refraction when doing curvature experiments". How does this all this theory translate into practical advice for someone like me who wants to design a valid experiment? I actually think this would be very valuable to both Flat Earthers and normal adults.
I'm clearly not an expert in the area but if I was to attempt to make some embarrassingly uneducated guesses, I'd think we would want in these experiments:
1. Cool/mild and stable temperatures at the time of the experiment and preceding hours. What is the ideal temperature range?
2. Low temperature differential between air and water so we don't get a layer of air just above the water that is significantly different from those above it. If the water was significantly colder than the air, we might get a dense colder layer above the water, if warmer it might be less dense than the air above it. What is the ideal temperature differential? Should the water be slightly cooler or warmer?
3. The higher the elevation the better for both observer and target. But if the temperature differential is not extreme, most temperature inversions would dissipate after the first few metres above the water when dealing with a small lake? This is just a guess and it seems it gets pretty complex when looking at the marine layer over the ocean. Target height is obviously a consideration too.